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OSHA Directives
CPL 2.106 - Enforcement Procedures and Scheduling for Occupational Exposure to Tuberculosis

 Part 1 of 2

SUBJECT: Enforcement Procedures and Scheduling for Occupational Exposure to Tuberculosis

A. Purpose. This instruction provides uniform inspection procedures and guidelines to be followed when conducting inspections and issuing citations under Section 5(a)(1) of the OSH Act and pertinent standards for employees who are occupationally exposed to tuberculosis.

B. Scope. This instruction applies OSHA-wide.

C. References.

1. OSHA Instruction CPL 2.103, September 26, 1994, Field Inspection Reference Manual (FIRM).

2. OSHA Instruction CPL 2.45B, June 15, 1985, The Revised Field Operations Manual (FOM).

3. American Public Health Association - 1990 or current edition, Control of Communicable Diseases in Man.

4. OSHA Instruction CPL 2-2.20B, CH-3, August 22, 1994. Occupational Safety and Health Administration Technical Manual Chapter No. 7.

5. OSHA Instruction, ADM 1-31, the IMIS Enforcement Data Processing Manual.

6. OSHA Instruction ADM 1-32, Enforcement User Skills Manual (for those Area Offices still using the NCR system).

7. Centers for Disease Control and Prevention (CDC), Biosafety in Microbiological and Biomedical Laboratories, 3rd Edition, or current edition.

8. Department of Health and Human Services, Public Health Service, 42 CFR Part 84; Final Rule

9. Centers for Disease Control and Prevention (CDC); Guidelines for Preventing the transmission of mycobacterium tuberculosis in Health Care Facilities, 1994; MMWR October 26, 1994 Vol. 43, No. RR-13.

D. Action. OSHA Regional Administrators and Area Directors shall use this instruction to ensure uniformity when performing inspections for occupational exposures to tuberculosis (TB). The Directorate of Compliance Programs shall provide support as necessary to assist the Regional Administrators and Area Directors in enforcing this directive. Issuance of this directive cancels the Memorandum to Regional Administers dated October 8, 1993, and entitled Enforcement Policy and Procedures for Occupational Exposure to Tuberculosis.

E. Federal Program Change. This is a federal program change which impacts state programs.

1. The Regional Administrator (RA) shall ensure that this change is promptly forwarded to each state designee using a format consistent with the Plan Change Two-way Memorandum in Appendix A, State Plan Policies and Procedures Manual (SPM).

2. The RA shall explain the content of this change to the state designee as required.

3. The state shall respond to this change within 70 days in accordance with paragraph I.1.a.(2).(a). and (b)., Part I, Chapter III of the SPM.

4. The state's acknowledgment shall include (a) the state's plan to adopt and implement an identical change, (b) the state's plan to develop an alternative, which is as effective, or the reasons why no change is necessary to maintain a program which is as effective. The state shall submit a plan supplement within six months in accordance with I.1.a.(3).(c)., Part I, Chapter III of the SPM.

5. The RA shall advise state designees of the following:

a. In order to ensure a sound and consistent national enforcement and litigation strategy in relation to complex issues addressed by this instruction, state implementation of the procedures in this instruction, or comparable state procedures, must be carefully coordinated with OSHA.

b. The state is also responsible for extending coverage under its procedures for addressing occupational exposure to tuberculosis to the public sector employees in workplaces covered by this instruction.

c. The Directorate of Technical Support is available to assist the states in locating expert witnesses (see paragraph M., expert witnesses). Also, the Directorate of Compliance Programs will provide support to the states through the RA to assist in the enforcement of this directive.

6. The RA shall review policies, instructions, and guidelines issued by the state to determine that this change has been communicated to state compliance personnel.

F. Definitions. For a complete list of definitions applicable to tuberculosis please refer to the list of definitions in the 1994 CDC guidelines found in Appendix A beginning on page 113.

G. Background. Since 1985, the incidence of tuberculosis (TB) in the general U.S. population has increased approximately 14 percent, reversing a 30-year downward trend. In 1993, 25,313 new cases of TB were reported in the United States. Increases in the incidence of TB have been observed in some geographic areas; these increases are related partially to the high risk for TB among immunosuppressed persons, particularly those infected with human immunodeficiency virus (HIV). Other factors (e.g., socioeconomic) have also contributed to these increases. Outbreaks have occurred in hospitals, correctional institutions, homeless shelters, nursing homes, and residential care facilities for AIDS patients. During 1994 and 1995 there has been a decrease in the number of TB cases in the United States that is likely been due to increased awareness and efforts in the prevention and control of TB, including the implementation of TB control measures recommended by the CDC and required by OSHA.

Recently, drug resistant strains of M. tuberculosis have become a serious concern and cases of multi-drug-resistant (MDR) TB have occurred in forty states. In a recent New York City study, 33% of cases had organisms resistant to the two most effective drugs available for treating the disease.

When organisms are resistant to both drugs, the course of the treatment increases from six months to 18-24 months, and the cure rate decreases from 100% to 60% or less.

In a 1992 American Hospital Association survey/CDC survey, 90 of 729 (13%) respondents reported nosocomial TB transmission to health care workers. More than 80% of those facilities experienced TB skin test conversions among workers. More than 100 cases of active TB disease in health care workers were known to CDC and reported to Congress by Dr. William Roper in the Spring of 1993. Twelve (12) health care workers have died. Nationwide, at least several hundred employees have become infected and required medical treatment after workplace exposure to TB. In general, persons who become infected with TB have approximately a 10% risk for developing active TB in their lifetimes.

M. tuberculosis is carried through the air in tiny infectious droplet nuclei of 1 to 5 microns in diameter. These droplets may be generated when a person with pulmonary and laryngeal TB disease coughs, speaks, sings, sneezes, or spits. When inhaled by susceptible persons, the mycobacteria in these droplets may become established in the lungs and, in some cases, spread throughout the body. After an interval of months, years, or even decades, the initial infection may then progress to clinical illness (i.e., tuberculosis disease). Transmission of TB is most likely to occur from persons with pulmonary or laryngeal TB that are not on effective anti-TB therapy and who have not been placed in respiratory isolation.

In occupational healthcare settings, where patients with TB are seen, workers exposed to tuberculosis droplet nuclei are at increased risk of infection with exposure to TB. Certain high-risk medical procedures that are cough-inducing or aerosol generating can further increase the risk of infection in health-care workers.

The employer's obligations are those set forth in the Occupational Safety and Health Act (OSH Act) of 1970. Recommendations for preventing the transmission of TB for health care settings were originally established with the 1990 CDC Guidelines. In October, of 1994, those guidelines were revised and published (Appendix A). The new guidelines emphasize the control of TB through an effective TB infection control program. Under these guidelines the control of TB is to be accomplished through the early identification, isolation, and treatment of persons with TB, use of engineering and administrative procedures to reduce the risk of exposure, and through the use of respiratory protection. OSHA believes these guidelines reflect an industry recognition of the hazard as well as appropriate, widely recognized, and accepted standards of practice to be followed by employers in carrying out their responsibilities under the OSH Act.

H. Inspection Scheduling and Scope

1. The evaluation of occupational exposure to TB shall be conducted in response to employee complaints, related fatality/catastrophes, or as part of all industrial hygiene inspections conducted in workplaces where the CDC has identified workers as having a greater incidence of TB infection than in the general population. The degree of risk of occupational exposure of a worker to TB will vary based on a number of factors discussed in detail by the CDC (Appendix A, pg. 4-5). These workplaces have been the subject of reports issued by the CDC which provide recommendations for the control of tuberculosis. Specifically, these workplaces are as follows:

a. health care facilities b. correctional institutions c. long-term care facilities for the elderly d. homeless shelters e. drug treatment centers

Note: Health-care facilities include hospitals where patients with confirmed or suspect TB are treated or to which they are transported. Coverage of non-hospital health care settings (i.e., doctors' offices, clinics, etc.) includes only personnel present during the performance of high hazard procedures on suspect or active TB patients. Dental health care personnel are covered by the directive only if they treat suspect or active patients in a hospital or correctional facility.

Homeless shelters - due to a variety of circumstances, the control of TB in homeless shelters presents unique problems for the protection of workers. Shelters must establish protocols that provide for rapid early identification followed by immediate transfer of suspect cases if the shelters have elected not to treat these patients.

2. All inspections in these workplaces shall include a review of the employer's plans for employee TB protection, if any. Such plans may include the infection control program, respiratory protection and skin testing. Employee interviews and site observations are an integral part of the process evaluation.

3. Complaints received from state and local government employees who are outside federal jurisdiction in federal enforcement states shall be referred to the appropriate agency by the Area Office.

I. Inspection Procedures. The procedure given in the FIRM, Chapter II, shall be followed except as modified in the following sections:

1. Health care facilities generally have internal infection control and employee health programs. This function may be performed by a team or individual. Upon entry, the CSHO shall request the presence of the infection control director and employee occupational health professional responsible for occupational health hazard control. Other individuals who will be responsible for providing records pertinent to the inspection may include: training director, facilities engineer, director of nursing, etc.

2. The CSHO shall establish whether or not the facility has had a suspect or confirmed TB case within the previous six (6) months from the opening conference to determine coverage under the OSH Act. This determination may be based upon interviews and, in a hospital, a review of the infection control data.

3. If the facility has had a suspect or confirmed TB case within the previous six months, the CSHO shall proceed with the TB portion of the inspection. The CSHO shall verify implementation of the employer's plans for TB protection through employee interviews and direct observation where feasible. Professional judgment shall be used to identify which areas of a facility must be inspected during the walkthrough (e.g., emergency rooms, respiratory therapy areas, bronchoscopy suites, and morgue). After review of the facility plans for worker TB protection, employee interviews combined with an inspection of appropriate areas of the facility, shall be used to determine compliance.

4. CSHOs who perform smoke-trail visualization tests should review the protocol in Appendix B of this directive.

5. CSHOs should be prepared to present to the employer the material safety data sheet (MSDS) for the smoke that is released on a smoke-trail visualization.

J. Compliance Officer Protection

1. Area Directors or Assistant Area Directors shall ensure that CSHOs performing TB related inspections are familiar with the CDC Guidelines, terminology, and are adequately trained through either course work or field/work experience in health care settings. Consultation with the regional TB coordinators is encouraged prior to beginning such inspections.

2. CSHOs shall not enter occupied respiratory isolation [AFB (acid fast bacilli)] rooms to evaluate compliance unless, in their determination entry is required to document a violation. Prior to entry CSHOs will discuss the need for entry with the Area Director. Photographs or video taping where practical shall be used for case documentation. Under no circumstances shall photographing or videotaping of patients be done. CSHO's must take all necessary precautions to assure and protect patient confidentiality.

3. CSHOs shall exercise professional judgement and extreme caution when engaging in activities that may involve potential exposure to TB. CSHOs normally shall establish the existence of hazards and adequacy of work practices through employee interviews and shall observe them in a manner which prevents exposure (e.g., through an observation window where available).

4. On rare occasions when entry into potentially hazardous areas is judged necessary (e.g., where the CSHO determines that direct observation of a high hazard procedure is necessary), the CSHO shall be properly equipped as required by the facility, this directive, and following consultation with the CSHO's supervisor. Since CSHOs' respiratory protection is used in more than one type of industry they shall use their negative pressure elastomeric face piece respirators equipped with HEPA filters as the minimum level of respiratory protection.

5. CSHOs who conduct TB inspections shall have been offered the TB skin tests. CSHOs exposed to an individual(s) with active infectious TB shall receive a follow-up examination and follow Sections J. and K. of Appendix A beginning on page 37.

Note: A "TB Skin Test" means the intradermal injection (Mantoux Method) of tuberculin antigen (usually PPD) with subsequent measurement of the induration by designated, trained personnel.

6. If an isolation room is occupied by a patient with confirmed or suspect TB or has not been adequately purged when a smoke-trail test is performed, then the CSHO should assume that the isolation room is not under negative pressure. Under such circumstances CSHOs shall wear a negative pressure HEPA respirator when performing air tests as described in Appendix B or if entry into the room is determined to be necessary.

K. Citation Policy. Relevant chapters of the FIRM shall be followed when preparing and issuing citations for hazards related to TB.

1. The following requirements apply when citing hazards found in target workplaces. Employers must comply with the provisions of these requirements whenever an employee may be occupationally exposed to TB:

Section 5(a)(1) -- General Duty Clause and Executive Order 12196, Section 1-201(a) for Federal facilities.

29 CFR 1910.134 -- Respiratory Protection

29 CFR 1910.145 -- Accident Prevention Signs and Tags

29 CFR 1910.20 -- Access to Employee Exposure and Medical Records

29 CFR 1904 -- Recording and Reporting Occupational Injuries & Illness

L. Violations. All elements in this section must be addressed to ensure adequate protection of employees from TB hazards. Violations of these OSHA requirements will normally be classified as serious.

1. General Duty Clause - Section 5(a)(1). Section 5(a)(1) provides: "Each employer shall furnish to each of his employees employment and a place of employment which are free from recognized hazards that are causing or are likely to cause death or serious physical harm to his employees."

a. Section 5(a)(1) citations must meet the requirements outlined in the FIRM, and shall be issued only when there is no standard that applies to the particular hazard. The hazard, not the absence of a particular means of abatement, is the basis for a general duty clause citation. All applicable abatement methods identified as correcting the same hazard shall be issued under a single 5(a)(1) citation.

b. Recognition, for purposes of citing section 5(a)(1), is shown by the CDC Guidelines for the types of exposures detailed below because the CDC is an acknowledged body of experts familiar with the hazard.

c. Citations shall be issued to employers with employees working in one of the workplaces where the CDC has identified workers as having a higher incidence of TB infection than the general population, when the employees are not provided appropriate protection and who have exposure as defined below:

1. Exposure to the exhaled air of an individual with suspected or confirmed pulmonary TB disease, or

Note: A suspected case is one in which the facility has identified an individual as having symptoms consistent with TB. The CDC has identified the symptoms to be: productive cough, coughing up blood, weight loss, loss of appetite, lethargy/weakness, night sweats, or fever.

2. Employee exposure without appropriate protection to a high hazard procedure performed on an individual with suspected or confirmed infectious TB disease and which has the potential to generate infectious airborne droplet nuclei. Examples of high hazard procedures include aerosolized medication treatment, bronchoscopy, sputum induction, endotracheal intubation and suctioning procedures, emergency dental, endoscopic procedures, and autopsies conducted in hospitals.

d. If a citation under 5(a)(1) is justified, the citation, after setting forth the SAVE for section 5(a)(1), shall state:

Section 5(a)(1) of the Occupational Safety and Health Act of 1970: The employer did not furnish employment and a place of employment which were free from recognized hazards that were causing or likely to cause death or serious physical harm to employees exposed to the hazard of being infected with Mycobacterium tuberculosis through unprotected contact with [specify group such as patients, inmates, clients, etc.] who was/were infectious or suspected to be infectious with tuberculosis in that: [list deficiencies]

Feasible and useful abatement methods for reducing this hazard, as recommended by the CDC, include, but are not limited to: [list abatement methods].

e. The following are examples of feasible and useful abatement methods, which must be implemented to abate the hazard. Deficiencies found in any category can result in the continued existence of a serious hazard and may, therefore, allow citation under 5(a)(1).

1. Early Identification of Patient/Client. The employer shall implement a protocol for the early identification of individuals with active TB. See Appendix A pages 19-30.

2. Medical Surveillance:

a. Initial Exams. The employer, in covered workplaces, shall offer TB skin tests (at no cost to the employees) to all current potentially exposed employees and to all new employees prior to exposure. A two-step baseline shall be used for new employees who have an initially negative PPD test result and who have not had a documented negative TB skin test result during the preceding 12 months (See Appendix A, pg. 63). TB skin tests shall be offered at a time and location convenient to workers. Follow-up and treatment evaluations are also to be offered at no cost to the workers.

Note: The reading and interpretation of the TB skin tests shall be performed by a qualified individual as described in the CDC Guidelines.

b. Periodic Evaluations. TB skin testing shall be conducted every three (3) months for workers in high risk categories, every six (6) months for workers in intermediate risk categories, and annually for low risk personnel (The CDC has defined the criteria for high, intermediate, and low risk categories, see Appendix A, pg. 8-17). Workers with a documented positive TB skin test who have received treatment for disease or preventive therapy for infection are exempt from the TB skin test but must be informed periodically about the symptoms of TB and the need for immediate evaluation of any pulmonary symptoms suggestive of TB by a physician or trained health care provider to determine if symptoms of TB disease have developed.

Note: If the facility has not completed a risk assessment the CSHO shall review the TB related records to establish required testing frequencies for the facility and areas of the facility.

c. Reassessment following exposure or change in health. Workers who experience exposure to an individual with suspect or confirmed infectious TB for whom infection control precautions have not been taken shall be managed according to CDC recommendations (Appendix A). An employee who develops symptoms of TB disease shall be immediately evaluated according to the CDC Guidelines.

3. Case Management of Infected Employees shall include the following:

a. Protocol for New Converters. Conversion to a positive TB skin test shall be followed as soon as possible, by appropriate physical, laboratory, and radiographic evaluations to determine whether the employee has infectious TB disease. (See Appendix A, pg. 65).

b. Work Restrictions for Infectious Employees. See Appendix A, page 41.

4. Worker Education and Training. Training and information to ensure employee knowledge of such issues as the mode of TB transmission, its signs and symptoms, medical surveillance and therapy, and site specific protocols including the purpose and proper use of controls shall be provided to all current employees and to new workers upon hiring. (See Appendix A, pgs. 36-37) Training should be repeated as needed.

Workers shall be trained to recognize, and report to a designated person, any patients or clients with symptoms suggestive of infectious TB and instructed on the post exposure protocols to be followed in the event of an exposure incident. (See Appendix A, pg. 23)

5. Engineering Controls. The use of each control measure must be based on its ability to abate the hazard.

a. Individuals with suspected or confirmed infectious TB disease must be placed in a respiratory acid-fast bacilli (AFB) isolation room. High hazard procedures on individuals with suspected or confirmed infectious TB disease must be performed in AFB treatment rooms, AFB isolation rooms, booths, and/or hoods. AFB isolation refers to a negative pressure room or an area that exhausts room air directly outside or through HEPA filters if recirculation is unavoidable.

b. Isolation and treatment rooms in use by individuals with suspected or confirmed infectious TB disease shall be kept under negative pressure to induce airflow into the room from all surrounding areas (e.g., corridors, ceiling plenums, plumbing chases, etc.). (See Appendix A, Supplement No. 3, page 76)

Note: The employer must assure that AFB isolation rooms are maintained under negative pressure. At a minimum, the employer must use nonirritating smoke trails or some other indicator to demonstrate that direction of airflow is from the corridor into the isolation/treatment room with the door closed. If an anteroom exists, direction of airflow must be demonstrated at the inner door between the isolation/treatment room and the anteroom. (See Appendix B)

c. Air exhausted from AFB isolation or treatment rooms must be safely exhausted directly outside and not recirculated into the general ventilation system. (See Appendix A, Supplement No. 3, page 87).

In circumstances where recirculation is unavoidable, HEPA filters must be installed in the duct system from the room to the general ventilation system. (See Appendix A, Supplement No. 3, page 82). For these HEPA filters, a regularly scheduled monitoring program to demonstrate as-installed effectiveness should include; 1) recognized field test method, 2) acceptance criteria, and 3) testing frequencies (see Appendix A, Supplement No. 3, page 85). The air handling system should be appropriately marked with a TB warning where maintenance personnel would have access to the duct work, fans, or filters for maintenance or repair activities.

d. In order to avoid leakage, all potentially contaminated air which is ducted through the facility must be kept under negative pressure until it is discharged safely outside (i.e., away from occupied areas and air intakes), or

e. The air from isolation and treatment rooms must be decontaminated by a recognized process (e.g., HEPA filter) before being recirculated back to the isolation/treatment room. The use of UV radiation as the sole means of decontamination shall not be used. The CDC Guidelines allow the use of UV in waiting rooms, emergency rooms, corridors, and the like where patients with undiagnosed TB could potentially contaminate the air. (See appendix A, pg. 90)

Note: The opening and closing of doors in an isolation or treatment room which is not equipped with an anteroom compromises the ability to maintain negative pressure in the room. For these rooms, the employer should utilize a combination of controls and practices to minimize spillage of contaminated air into the corridor. Recognized controls and practices include, but are not limited to: minimizing entry to the room; adjusting the hydraulic closer to slow the door movement and reduce displacement effects; adjusting doors to swing into the room where fire codes permit; avoiding placement of room exhaust intake near the door; etc.

f. If high-hazard procedures are performed within AFB isolation or treatment rooms without benefit of source control ventilation or local exhaust ventilation (e.g., hood, booth, tent, etc.), and droplets are released into the environment (e.g., coughing), then a purge time interval must be imposed during which personnel must use a respirator when entering the room. (See Appendix A, pg. 35 and Suppl. 3, Table S3-1)

g. Interim or supplemental ventilation units equipped with HEPA filters as described in Appendix A pgs. 70-73 are acceptable.

2. Respiratory Protection - 29 CFR 1910.134(a)(2) and (b). The standard provides in part:

"Respirators shall be provided by the employer when such equipment is necessary to protect the health of the employee. The employer shall provide the respirators which are applicable and suitable for the purpose intended. The employer shall be responsible for the establishment and maintenance of a respiratory protective program which shall include the requirement outlined in paragraph (b) of this section."

a. Requirements for a minimal acceptable program. The 1994 CDC Guidelines specify standard performance criteria for respirators for exposure to TB. These criteria include (see appendix A pg 97):

1. The ability to filter particles 1 um in size in the unloaded state with a filter efficiency of greater than or equal to 95% (i.e., filter leakage of less than or equal to 5%), given flow rates of up to 50L per minute.

2. The ability to be qualitatively or quantitatively fit tested in a reliable way to obtain a face-seal leakage of less than or equal to 10%.

3. The ability to fit the different facial sizes and characteristics of health care workers which can usually be met by making the respirators available in at least three sizes.

4. The ability to be checked for face piece fit, in accordance with OSHA standards and good industrial hygiene practice, by health care workers each time they put on their respirator.

b. Under the new NIOSH criteria, filter materials would be tested at a flow rate of 85 L/minute for penetration by particles with a median aerodynamic diameter of 0.3 um and, if certified would be placed in one of the following categories: Type 100 (99.7% efficient), Type 99 (99% efficient), and Type 95 (95% efficient). NIOSH has determined that these categories of respirators are effective against TB. Based upon these criteria, the minimally acceptable level of respiratory protection for TB is the Type 95 Respirator. The classes of these air-purifying, particulate respirators to be certified are described under 42 CFR Part 84 Subpart K. See Volume 60 of the Federal Register, page 30338 (June 8, 1995). Until these classes of respirators are commercially available the minimal acceptable respiratory protection meeting the criteria will remain the HEPA respirator (see Appendix A, pg 98). The following respiratory protection measures must be addressed:

1. Employees wear HEPA or respirators certified under 42 CFR Part 84 Subpart K in the following circumstances:

a. When workers enter rooms housing individuals with suspected or confirmed infectious TB.

b. When workers are present during the performance of high hazard procedures on individuals who have suspected or confirmed infectious TB.

c. When emergency-medical-response personnel or others transport, in a closed vehicle, an individual with suspected or confirmed infectious TB.

Note: If a facility chooses to use disposable respirators as part of their respiratory protection program, their reuse by the same health care worker is permitted as long as the respirator maintains its structural and functional integrity and the filter material is not physically damaged or soiled. The facility must address the circumstances in which a disposable respirator will be considered to be contaminated and not available for reuse.

2. The following sample language is provided for citations which are warranted under 1910.134(a)(2):

"The employer did not provide respirators which were applicable and suitable for the purpose intended, nor was a respiratory protection program established which included the requirements outlined in 29 CFR 1910.134(b):

(a) Employees were given a [surgical mask or list manufacturer/model number] respirator for protection against airborne Mycobacterium tuberculosis when entering isolation rooms or performing high hazard procedures [including vehicular transporting if applicable]. They shall use NIOSH approved respirators (HEPA or those certified under 42 CFR Part 84 Subpart K).

NIOSH approved respirators providing greater protection would also be acceptable.

3. When respiratory protection (including disposable respirators) is required, a complete respiratory protection program must be in place in accordance with 29 CFR 1910.134(b).

3. Access to employee medical and exposure records: 29 CFR 1910.20.

a. A record concerning employee exposure to TB is an employee exposure record within the meaning of 29 CFR 1910.20.

b. A record of TB skin test results and medical evaluations and treatment are employee medical records within the meaning of 29 CFR 1910.20. Where known, the workers exposure record should contain a notation of the type of TB, to which the employee was exposed to (e.g., multidrug resistant TB).

c. These records shall be handled according to 29 CFR 1913.10 in order for the CSHO to determine compliance with 29 CFR 1910.20.

4. Accident prevention signs and tags: 29 CFR 1910.145.

a. In accordance with 1910.145(f)(8), a warning shall be posted outside the Respiratory isolation or treatment room. 1910.145(f)(4) requires that a signal word (i.e. "STOP", "HALT", or "NO ADMITTANCE") or biological hazard symbol be presented as well as a major message (e.g., "special respiratory isolation", "Respiratory isolation", or AFB isolation). A description of the necessary precautions, e.g., respirators must be donned before entering. Respiratory isolation rooms in an emergency department or a message referring one to the nursing station for instruction must also be posted.

b. The employer shall also use biological hazard tags on air transport components (e.g., fans, ducts, filters) which identify TB hazards to employees associated with working on air systems that transport contaminated air (See Appendix A, page 85).

c. The standard provides in part:

29 CFR 1910.145(e)(4): Biological hazard warning signs were not used to signify the actual or potential presence of a biohazard and to identify equipment, containers, rooms, materials, experimental animals, or combinations thereof, which contain, or are contaminated with viable hazardous agents:

Sample violation language:

a. On or about [date], warning signs posted outside respiratory (Respiratory) isolation or treatment rooms did not state the entry requirement of wearing HEPA filtered respirators.

Abatement Note: Warning signs must be posted on respiratory isolation or treatment rooms stating "pulmonary isolation", "respiratory isolation," or "AFB isolation." The sign must state specifically the precautions required to interact with those patients. Indicators on patient records or tags on corpses, printed in language or symbols easily recognized by employees are additional methods to achieve this purpose.

5. OSHA 200 log - 29 CFR 1904:

a. For OSHA Form 200 record keeping purposes, both tuberculosis infections (positive TB skin test) and tuberculosis disease are recordable in the high risk setting referenced in section H.1. A positive skin test for tuberculosis, even on initial testing (except pre-assignment screening) is recordable on the OSHA 200 log because there is a presumption of work-relatedness in these settings unless there is clear documentation that an outside exposure occurred.

Note: In this case preassignment means the same as pre employment and initial testing is the same as baseline testing.

b. If the employee's tuberculosis infection which was entered on the OSHA 200 log progresses to tuberculosis disease during the five-year maintenance period, the original entry for the infection shall be updated to reflect the new information. Because it is difficult to determine if tuberculosis disease resulted from the source indicated by the skin test conversion or from subsequent exposures, only one case should be entered to avoid double counting.

c. A positive TB skin test provided within two weeks of employment does not have to be recorded on the OSHA 200 forms. However, the initial test must be performed prior to any potential workplace exposure within the initial two weeks of employment.

M. Expert Witness. The Directorate of Technical Support will assist Regional Offices and the States in locating expert witnesses. Expert witnesses must be contacted before issuance of citations.

1. In the event that a 5(a)(1) citation is contested, proper expert witness support will be required. Issues which the expert must be prepared to address include:

a. The risk to workers associated with the exposure circumstances.

b. Existence, feasibility and utility of abatement measures.

c. Recognition of the hazard in the industry.

2. Expert witnesses may also be necessary in other cases, particularly those involving 29 CFR 1910.134.

N. Recording in the IMIS. A TB-related inspection is any health inspection conducted to investigate the presence or alleged presence of TB disease (i.e., a referral or complaint inspection).

1. When a TB-related inspection is conducted, complete the OSHA-1 as for any inspection and enter the code "N 02 TB" in Item 42, Optional Information. EXAMPLE:

Type ID Value N 2 TB

2. When an OSHA-7 is completed and the complaint alleges the presence of TB hazards, enter the code "N 02 TB" in Item 46, Optional Information.

3. When an OSHA-90 is completed and the referral alleges the presence of TB hazards, enter the code "N 02 TB" in Item, 26, Optional Information.

4. All IMIS case file data for TB-related inspections conducted since October 1, 1990, shall be modified to include the appropriate TB code.

O. Referrals

1. When a complaint or inquiry is received from a source in a state plan regarding occupational exposure to TB, the Area Office shall refer it to the state plan designee for action.

2. When a complaint or inquiry regarding occupational exposure to TB in a state or local government health care facility is received in a state without an OSHA-approved state plan, the Regional Administrator shall refer it to the appropriate State public health agency or local health agency.

P. Pre-citation Review. Citations proposed pursuant to this program shall be reviewed prior to issuance, by the Regional Administrator and Regional Office Solicitor for consistency with these procedures. The Directorate of Technical Support shall be contacted to establish expert witness support. The Office of Health Compliance Assistance shall be provided with a copy of all citations issued related to TB during the first 6 months of this directive.

Joseph A. Dear Assistant Secretary

Distribution: National, Regional, and Area Offices All Compliance Officers State Designees NIOSH Regional Program Directors 7(c)(1) Consultation Project Managers

Appendix No. A

October 28, 1994/Vol. 43/No.RR-13

MMWR Recommendations and Reports

MORBIDITY AND MORTALITY WEEKLY REPORT

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  Guidelines for preventing the Transmission of Mycobacterium Tuberculosis in Health-Care Facilities, 1994

  U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES Public Health Service Centers for Disease Control and Prevention (CDC) Atlanta, Georgia 30333

Contents

  Executive Summary

I. Introduction

A. Purpose of Document

B. Epidemiology, Transmission, and Pathogenesis of TB

C. Risk for Nosocomial Transmission of M. tuberculosis

D. Fundamentals of TB Infection Control

II. Recommendations

A. Assignment of Responsibility

B. Risk Assessment, Development of the TB Infection-Control Plan, and Periodic Reassessment

1. Risk assessment

a. General

b. Community TB profile

c. Case surveillance

d. Analysis of HCW PPD test screening data

e. Review of TB patient medical records

f. Observation of TB infection-control practices

g. Engineering evaluation

2. Development of the TB Infection-Control Plan

3. Periodic Reassessment

4. Examples of Risk Assessment

C. Identifying, Evaluating, and Initiating Treatment for Patients Who May Have Active TB

1. Identifying patients who may have active TB

2. Diagnostic evaluation for active TB

3. Initiation of treatment for suspected or confirmed TB

D. Management of Patients Who May Have Active TB in Ambulatory-Care Settings and Emergency Departments

E. Management of Hospitalized Patients Who Have Confirmed or Suspected TB

1. Initiation of isolation for TB

2. TB isolation practices

3. The TB isolation room

4. Discontinuation of TB isolation

5. Discharge planning

F. Engineering Control Recommendations

1. General ventilation

2. Additional engineering control approaches

a. HEPA filtration

b. UVGI

G. Respiratory Protection

H. Cough-inducing and Aerosol-Generating Procedures

1. General guidelines

2. Special considerations for bronchoscopy

3. Special considerations for the administration of aerosolized pentamidine

I. Education and Training of HCWs

J. HCW Counseling, Screening, and Evaluation

1. Counseling HCWs regarding TB

2. Screening HCWs for active TB

3. Screening HCWs for latent TB infection

4. Evaluation and management of HCWs who have positive PPD test results or active TB

a. Evaluation

b. Routine and follow-up chest radiographs

c. Workplace restrictions

1) Active TB

2) Latent TB infection

K. Problem Evaluation

1. Investigating PPD test conversions and active TB in HCWs

a. Investigating PPD test conversions in HCWs

b. Investigating cases of active TB in HCWs

2. Investigating possible patient-to-patient transmission of M. tuberculosis

3. Investigating contacts of patients and HCWs who have infectious TB

L. Coordination with the Public Health Department

M. Additional Considerations for Selected Areas in Health-Care Facilities and Other Health-Care Settings

1. Selected areas in health-care facilities

a. Operating rooms

b. Autopsy rooms

c. Laboratories

2. Other health-care settings

a. Emergency medical services

b. Hospices

c. Long-term care facilities

d. Correctional facilities

e. Dental settings

f. Home-health-care settings

g. Medical offices

Supplement 1: Determining the Infectiousness of a TB Patient

Supplement 2: Diagnosis and Treatment of Latent TB Infection and Active TB

I. Diagnostic Procedures for TB Infection and Disease

A. PPD Skin Testing and Anergy Testing

1. Application and reading of PPD skin tests

2. Interpretation of PPD skin tests

a. General

b. HCWs

3. Anergy testing

4. Pregnancy and PPD skin testing

5. BCG vaccination and PPD skin testing

6. The booster phenomenon

B. Chest Radiography

C. Bacteriology

II. Preventive Therapy for Latent TB Infection and Treatment of Active TB

A. Preventive Therapy for Latent TB Infection

B. Treatment of Patients Who Have Active TB

Supplement 3: Engineering Controls

I. Introduction

II. Ventilation

A. Local Exhaust Ventilation

1. Enclosing devices

2. Exterior-devices

3. Discharge exhaust from booths, tents, and hoods

B. General Ventilation

1. Dilution and removal

a. Types of general ventilation systems

b. Ventilation rates

2. Airflow patterns within rooms (air mixing)

3. Airflow direction in the facility

a. Directional airflow

b. Negative pressure for achieving directional airflow

4. Achieving negative pressure in a room

a. Pressure differential

b. Alternate methods for achieving negative pressure

c. Monitoring negative pressure

C. HEPA filtration

1. Use of HEPA filtration when exhausting air to the outside

2. Recirculation of HEPA-filtered air to other areas of a facility

3. Recirculation of HEPA-filtered air within a room

a. Fixed room-air recirculation systems

b. Portable room-air recirculation units

c. Evaluation of room-air recirculation systems and units

4. Installing, maintaining, and monitoring HEPA filters

D. TB Isolation Rooms and Treatment Rooms

1. Preventing the escape of droplet nuclei from the room

2. Reducing the concentration of droplet nuclei in the room

3. Exhaust from TB isolation rooms and treatment rooms

4. Alternatives to TB isolation rooms

III. UVGI

A. Applications

1. Duct irradiation

2. Upper-room air irradiation

B. Limitations

C. Safety Issues

D. Exposure Criteria for UV Radiation

E. Maintenance and Monitoring

1. Labeling and posting

. Maintenance

3. Monitoring

Supplement 4: Respiratory Protection

I. Considerations for Selection of Respirators

A. Performance Criteria for Personal Respirators for Protection Against Transmission of M. tuberculosis

B. Specific Respirators

C. The Effectiveness of Respiratory Protective Devices

1. Face-seal leakage

2. Filter leakage

3. Fit testing

4. Fit checking

5. Reuse of respirators

II. Implementing a Personal Respiratory Protection Program

Supplement 5: Decontamination-Cleaning, Disinfecting, and Sterilizing of Patient-Care Equipment

References

Glossary

Index

List of Tables

List of Figures

  Acknowledgments

Drafts of this document have been reviewed by leaders of numerous medical, scientific, public health, and labor organizations and others expert in tuberculosis, acquired immunodeficiency syndrome, infection control, hospital epidemiology, microbiology, ventilation, industrial hygiene, nursing, dental practice, or emergency medical services. We thank the many organizations and individuals for their thoughtful comments, suggestions, and assistance.

  TB Infection-Control Guidelines Work Group

Carmine J. Bozzi Dale R. Burwen, M.D. Samuel W. Dooley, M.D. Patricia M. Simone, M.D. National Center for Prevention Services

Consuelo Beck-Sague, M.D. Elizabeth A. Bolyard, R.N., M.P.H. William R. Jarvis, M.D. National Center for Infectious Diseases

Philip J. Bierbaum Christine A. Hudson, M.P.H. Robert T. Hughes Linda S. Martin, Ph.D. Robert J. Mullan, M.D. National Institute for Occupational Safety and Health

Brian M. Willis, J.D., M.P.H. Office of the Director

  Guidelines for Preventing the Transmission of Mycobacterium tuberculosis in Health-Care Facilities, 1994

Executive Summary

This document updates and replaces all previously published guidelines for the prevention of Mycobacterium tuberculosis transmission in health-care facilities. The purpose of this revision is to emphasize the importance of a) the hierarchy of control measures, including administrative and engineering controls and personal respiratory protection; b) the use of risk assessments for developing a written tuberculosis (TB) control plan; c) early identification and management of persons who have TB; d) TB screening programs for health-care workers (HCWs); e) HCW training and education; and f) the evaluation of TB infection-control programs.

Transmission of M. tuberculosis is a recognized risk to patients and HCWs in health-care facilities. Transmission is most likely to occur from patients who have unrecognized pulmonary or laryngeal TB, are not on effective anti-TB therapy, and have not been placed in TB isolation. Several recent TB outbreaks in health-care facilities, including outbreaks of multidrug-resistant TB, have heightened concern about nosocomial transmission. Patients who have multidrug-resistant TB can remain infectious for prolonged periods, which increases the risk for nosocomial and/or occupational transmission of M. tuberculosis. Increases in the incidence of TB have been observed in some geographic areas; these increases are related partially to the high risk for TB among immunosuppressed persons, particularly those infected with human immunodeficiency virus (HIV). Transmission of M. tuberculosis to HIV-infected persons is of particular concern because these persons are at high risk for developing active TB if they become infected with the bacteria. Thus, health-care facilities should be particularly alert to the need for preventing transmission of M. tuberculosis in settings in which HIV-infected persons work or receive care.

Supervisory responsibility for the TB infection-control program should be assigned to a designated person or group of persons who should be given the authority to implement and enforce TB infection-control policies. An effective TB infection-control program requires early identification, isolation, and treatment of persons who have active TB. The primary emphasis of TB infection-control plans in health-care facilities should be achieving these three goals by the application of a hierarchy of control measures, including a) the use of administrative measures to reduce the risk for exposure to persons who have infectious TB, b) the use of engineering controls to prevent the spread and reduce the concentration of infectious droplet nuclei, and c) the use of personal respiratory protective equipment in areas where there is still a risk for exposure to M. tuberculosis (e.g., TB isolation rooms). Implementation of a TB infection-control program requires risk assessment and development of a TB infection-control plan; early identification, treatment, and isolation of infectious TB patients; effective engineering controls; an appropriate respiratory protection program; HCW TB training, education, counseling, and screening; and evaluation of the program's effectiveness.

Although completely eliminating the risk for transmission of M. tuberculosis in all health-care facilities may not be possible at the present time, adherence to these guidelines should reduce the risk to persons in these settings. Recently, nosocomial TB outbreaks have demonstrated the substantial morbidity and mortality among patients and HCWs that have been associated with incomplete implementation of CDC's Guidelines for Preventing the Transmission of Tuberculosis in Health-Care Facilities, with Special Focus on HIV-Related Issues published in 1990.* Follow-up investigations at some of these hospitals have documented that complete implementation of measures similar or identical to those in the 1990 TB Guidelines significantly reduced or eliminated nosocomial transmission of M. tuberculosis to patients and/or HCWs.

__________ * CDC. Guidelines for Preventing the Transmission of Tuberculosis in Health-Care Facilities, with Special Focus on HIV-Related Issues. MMWR 1990;39(No. RR-17).

I. Introduction

A. Purpose of Document

In April 1992, the National MDR-TB Task Force published the National Action Plan to Combat Multidrug-Resistant Tuberculosis (1). The publication was a response to reported nosocomial outbreaks of tuberculosis (TB), including outbreaks of multidrug-resistant TB (MDR-TB), and the increasing incidence of TB in some geographic areas. The plan called for the update and revision of the guidelines for preventing nosocomial transmission of Mycobacterium tuberculosis published December 7, 1990 (2).

Public meetings were held in October 1992 and January 1993 to discuss revision of the 1990 TB Guidelines (2). CDC received considerable input on various aspects of infection control, including health-care worker (HCW) education; administrative controls (e.g., having protocols for the early identification and management of patients who have TB); the need for more specific recommendations regarding ventilation; and clarification on the use of respiratory protection in health-care settings. On the basis of these events and the input received, on October 12, 1993, CDC published in the Federal Register the Draft Guidelines For Preventing the Transmission of Tuberculosis in Health-Care Facilities, Second Edition (3). During and after the 90-day comment period following publication of this draft, CDC's TB Infection-Control Guidelines Work Group received and reviewed more than 2,500 comments.

The purpose of this document is to make recommendations for reducing the risk for transmitting M. tuberculosis to HCWs, patients, volunteers, visitors, and other persons in these settings. The information also may serve as a useful resource for educating HCWs about TB.

These recommendations update and replace all previously published CDC recommendations for TB infection control in health-care facilities (2,4). The recommendations in this document are applicable primarily to inpatient facilities in which health care is provided (e.g., hospitals, medical wards in correctional facilities, nursing homes, and hospices). Recommendations applicable to ambulatory-care facilities, emergency departments, home-health-care settings, emergency medical services, medical offices, dental settings, and other facilities or residential settings that provide medical care are provided in separate sections, with cross-references to other sections of the guidelines if appropriate.

Designated personnel at health-care facilities should conduct a risk assessment for the entire facility and for each area* and occupational group, determine the risk for nosocomial or occupational transmission of M. tuberculosis, and implement an appropriate TB infection-control program. The extent of the TB infection-control program may range from a simple program emphasizing administrative controls in settings where there is minimal risk for exposure to M. tuberculosis, to a comprehensive program that includes administrative controls, engineering controls, and respiratory protection in settings where the risk for exposure is high. In all settings, administrative measures should be used to minimize the number of HCWs exposed to M. tuberculosis while still providing optimal care for TB patients. HCWs providing care to patients who have TB should be informed about the level of risk for transmission of M. tuberculosis and the appropriate control measures to minimize that risk.

__________ * Area: a structural unit (e.g., a hospital ward or laboratory) or functional unit (e.g., an internal medicine service) in which HCWs provide services to and share air with a specific patient population or work with clinical specimens that may contain viable M. tuberculosis organisms. The risk for exposure to M. tuberculosis in a given area depends on the prevalence of TB in the population served and the characteristics of the environment.

In this document, the term "HCWs" refers to all the paid and unpaid persons working in health-care settings who have the potential for exposure to M. tuberculosis. This may include, but is not limited to, physicians; nurses; aides; dental workers; technicians; workers in laboratories and morgues; emergency medical service (EMS) personnel; students; part-time personnel; temporary staff not employed by the health-care facility; and persons not involved directly in patient care but who are potentially at risk for occupational exposure to M. tuberculosis (e.g., volunteer workers and dietary, housekeeping, maintenance, clerical, and janitorial staff).

Although the purpose of this document is to make recommendations for reducing the risk for transmission of M. tuberculosis in health-care facilities, the process of implementing these recommendations must safeguard, in accordance with applicable state and federal laws, the confidentiality and civil rights of persons who have TB.

B. Epidemiology, Transmission, and Pathogenesis of TB

The prevalence of TB is not distributed evenly throughout all segments of the U.S. population. Some subgroups or persons have a higher risk for TB either because they are more likely than other persons in the general population to have been exposed to and infected with M. tuberculosis or because their infection is more likely to progress to active TB after they have been infected (5). In some cases, both of these factors may be present. Groups of persons known to have a higher prevalence of TB infection include contacts of persons who have active TB, foreign-born persons from areas of the world with a high prevalence of TB (e.g., Asia, Africa, the Caribbean, and Latin America), medically underserved populations (e.g., some African-Americans, Hispanics, Asians and Pacific Islanders, American Indians, and Alaskan Natives), homeless persons, current or former correctional-facility inmates, alcoholics, injecting-drug users, and the elderly. Groups with a higher risk for progression from latent TB infection to active disease include persons who have been infected recently (i.e., within the previous 2 years), children less than 4 years of age, persons with fibrotic lesions on chest radiographs, and persons with certain medical conditions (i.e., human immunodeficiency virus [HIV] infection, silicosis, gastrectomy or jejuno-ileal bypass, being greater than or equal to 10% below ideal body weight, chronic renal failure with renal dialysis, diabetes mellitus, immunosuppression resulting from receipt of high-dose corticosteroid or other immunosuppressive therapy, and some malignancies)(5).

M. tuberculosis is carried in airborne particles, or droplet nuclei, that can be generated when persons who have pulmonary or laryngeal TB sneeze, cough, speak, or sing (6). The particles are an estimated 1-5 um in size, and normal air currents can keep them airborne for prolonged time periods and spread them throughout a room or building (7). Infection occurs when a susceptible person inhales droplet nuclei containing M. tuberculosis, and these droplet nuclei traverse the mouth or nasal passages, upper respiratory tract, and bronchi to reach the alveoli of the lungs. Once in the alveoli, the organisms are taken up by alveolar macrophages and spread throughout the body. Usually within 2-10 weeks after initial infection with M. tuberculosis, the immune response limits further multiplication and spread of the tubercle bacilli; however, some of the bacilli remain dormant and viable for many years. This condition is referred to as latent TB infection. Persons with latent TB infection usually have positive purified protein derivative (PPD)-tuberculin skin-test results, but they do not have symptoms of active TB, and they are not infectious.

In general, persons who become infected with M. tuberculosis have approximately a 10% risk for developing active TB during their lifetimes. This risk is greatest during the first 2 years after infection. Immunocompromised persons have a greater risk for the progression of latent TB infection to active TB disease; HIV infection is the strongest known risk factor for this progression. Persons with latent TB infection who become coinfected with HIV have approximately an 8%-10% risk per year for developing active TB (8). HIV-infected persons who are already severely immunosuppressed and who become newly infected with M. tuberculosis have an even greater risk for developing active TB (9-12).

The probability that a person who is exposed to M. tuberculosis will become infected depends primarily on the concentration of infectious droplet nuclei in the air and the duration of exposure. Characteristics of the TB patient that enhance transmission include a) disease in the lungs, airways, or larynx; b) presence of cough or other forceful expiratory measures; c) presence of acid-fast bacilli (AFB) in the sputum; d) failure of the patient to cover the mouth and nose when coughing or sneezing; e) presence of cavitation on chest radiograph; f) inappropriate or short duration of chemotherapy; and g) administration of procedures that can induce coughing or cause aerosolization of M. tuberculosis (e.g., sputum induction). Environmental factors that enhance the likelihood of transmission include a) exposure in relatively small, enclosed spaces; b) inadequate local or general ventilation that results in insufficient dilution and/or removal of infectious droplet nuclei; and c) recirculation of air containing infectious droplet nuclei. Characteristics of the persons exposed to M. tuberculosis that may affect the risk for becoming infected are not as well defined. In general, persons who have been infected previously with M. tuberculosis may be less susceptible to subsequent infection. However, reinfection can occur among previously infected persons, especially if they are severely immunocompromised. Vaccination with Bacille of Calmette and Guerin (BCG) probably does not affect the risk for infection; rather, it decreases the risk for progressing from latent TB infection to active TB (13). Finally, although it is well established that HIV infection increases the likelihood of progressing from latent TB infection to active TB, it is unknown whether HIV infection increases the risk for becoming infected if exposed to M. tuberculosis.

C. Risk for Nosocomial Transmission of M. tuberculosis

Transmission of M. tuberculosis is a recognized risk in health-care facilities (14-22). The magnitude of the risk varies considerably by the type of health-care facility, the prevalence of TB in the community, the patient population served, the HCW's occupational group, the area of the health-care facility in which the HCW works, and the effectiveness of TB infection-control interventions. The risk may be higher in areas where patients with TB are provided care before diagnosis and initiation of TB treatment and isolation precautions (e.g., in clinic waiting areas and emergency departments) or where diagnostic or treatment procedures that stimulate coughing are performed. Nosocomial transmission of M. tuberculosis has been associated with close contact with persons who have infectious TB and with the performance of certain procedures (e.g., bronchoscopy [17], endotracheal intubation and suctioning [18], open abscess irrigation [20], and autopsy [21,22]). Sputum induction and aerosol treatments that induce coughing may also increase the potential for transmission of M. tuberculosis (23,24). Personnel of health-care facilities should be particularly alert to the need for preventing transmission of M. tuberculosis in those facilities in which immunocompromised persons (e.g., HIV-infected persons) work or receive care -- especially if cough-inducing procedures, such as sputum induction and aerosolized pentamidine treatments, are being performed.

Several TB outbreaks among persons in health-care facilities have been reported recently (11,24-28; CDC, unpublished data). Many of these outbreaks involved transmission of multidrug-resistant strains of M. tuberculosis to both patients and HCWs. Most of the patients and some of the HCWs were HIV-infected persons in whom new infection progressed rapidly to active disease. Mortality associated with those outbreaks was high (range: 43%-93%). Furthermore, the interval between diagnosis and death was brief (range of median intervals: 4-16 weeks). Factors contributing to these outbreaks included delayed diagnosis of TB, delayed recognition of drug resistance, and delayed initiation of effective therapy -- all of which resulted in prolonged infectiousness, delayed initiation and inadequate duration of TB isolation, inadequate ventilation in TB isolation rooms, lapses in TB isolation practices and inadequate precautions for cough-inducing procedures, and lack of adequate respiratory protection. Analysis of data collected from three of the health-care facilities involved in the outbreaks indicates that transmission of M. tuberculosis decreased significantly or ceased entirely in areas where measures similar to those in the 1990 TB Guidelines were implemented (2,29-32). However, several interventions were implemented simultaneously, and the effectiveness of the separate interventions could not be determined.

D. Fundamentals of TB Infection Control

An effective TB infection-control program requires early identification, isolation, and effective treatment of persons who have active TB. The primary emphasis of the TB infection-control plan should be on achieving these three goals. In all health-care facilities, particularly those in which persons who are at high risk for TB work of receive care, policies and procedures for TB control should be developed, reviewed periodically, and evaluated for effectiveness to determine the actions necessary to minimize the risk for transmission of M. tuberculosis.

The TB infection-control program should be based on a hierarchy of control measures. The first level of the hierarchy, and that which affects the largest number of persons, is using administrative measures intended primarily to reduce the risk for exposing uninfected persons to persons who have infectious TB. These measures include a) developing and implementing effective written policies and protocols to ensure the rapid identification, isolation, diagnostic evaluation, and treatment of persons likely to have TB; b) implementing effective work practices among HCWs in the health-care facility (e.g., correctly wearing respiratory protection and keeping doors to isolation rooms closed); c) educating, training, and counseling HCWs about TB; and d) screening HCWs for TB infection and disease.

The second level of the hierarchy is the use of engineering controls to prevent the spread and reduce the concentration of infectious droplet nuclei. These controls include a) direct source control using local exhaust ventilation, b) controlling direction of airflow to prevent contamination of air in areas adjacent to the infectious source, c) diluting and removing contaminated air via general ventilation, and d) air cleaning via air filtration or ultraviolet germicidal irradiation (UVGI).

The first two levels of the hierarchy minimize the number of areas in the health-care facility where exposure to infectious TB may occur, and they reduce, but do not eliminate, the risk in those few areas where exposure to M. tuberculosis can still occur (e.g., rooms in which patients with known or suspected infectious TB are being isolated and treatment rooms in which cough-inducing or aerosol-generating procedures are performed on such patients). Because persons entering such rooms may be exposed to M. tuberculosis, the third level of the hierarchy is the use of personal respiratory protective equipment in these and certain other situations in which the risk for infection with M. tuberculosis may be relatively higher.

Specific measures to reduce the risk for transmission of M. tuberculosis include the following:

* Assigning to specific persons in the health-care facility the supervisory responsibility for designing, implementing, evaluating, and maintaining the TB infection-control program (Section II.A).

* Conducting a risk assessment to evaluate the risk for transmission of M. tuberculosis in all areas of the health-care facility, developing a written TB infection-control program based on the risk assessment, and periodically repeating the risk assessment to evaluate the effectiveness of the TB infection-control program (Section II.B).

* Developing, implementing, and enforcing policies and protocols to ensure early identification, diagnostic evaluation, and effective treatment of patients who may have infectious TB (Section II.C; Suppl. 2).

* Providing prompt triage for and appropriate management of patients in the outpatient setting who may have infectious TB (Section II.D).

* Promptly initiating and maintaining TB isolation for persons who may have infectious TB and who are admitted to the inpatient setting (Section II.E; Suppl. 1).

* Effectively planning arrangements for discharge (Section II.E).

* Developing, installing, maintaining, and evaluating ventilation and other engineering controls to reduce the potential for airborne exposure to M. tuberculosis (Section II.F; Suppl. 3).

* Developing, implementing, maintaining, and evaluating a respiratory protection program (Section II.G; Suppl. 4).

* Using precautions while performing cough-inducing procedures (Section II.H; Suppl. 3).

* Educating and training HCWs about TB, effective methods for preventing transmission of M. tuberculosis, and the benefits of medical screening programs (Section II.I).

* Developing and implementing a program for routine periodic counseling and screening of HCWs for active TB and latent TB infection (Section II.J; Suppl. 2).

* Promptly evaluating possible episodes of M. tuberculosis transmission in health-care facilities, including PPD skin-test conversions among HCWs, epidemiologically associated cases among HCWs or patients, and contacts of patients or HCWs who have TB and who were not promptly identified and isolated (Section II.K).

* Coordinating activities with the local public health department, emphasizing reporting, and ensuring adequate discharge follow-up and the continuation and completion of therapy (Section II.L).

II. Recommendations

A. Assignment of Responsibility

* Supervisory responsibility for the TB infection-control program should be assigned to a designated person or group of persons with expertise in infection control, occupational health, and engineering. These persons should be given the authority to implement and enforce TB infection-control policies.

* If supervisory responsibility is assigned to a committee, one person should be designated as the TB contact person. Questions and problems can then be addressed to this person.

B. Risk Assessment, Development of the TB Infection-Control Plan, and Periodic Reassessment

1. Risk assessment

a. General

* TB infection-control measures for each health-care facility should be based on a careful assessment of the risk for transmission of M. tuberculosis in that particular setting. The first step in developing the TB infection-control program should be to conduct a baseline risk assessment to evaluate the risk for transmission of M. tuberculosis in each area and occupational group in the facility (Table 1, Figure 1). Appropriate infection-control interventions can then be developed on the basis of actual risk. Risk assessments should be performed for all inpatient and outpatient settings (e.g., medical and dental offices).

* Regardless of risk level, the management of patients with known or suspected infectious TB should not vary. However, the index of suspicion for infectious TB among patients, the frequency of HCW PPD skin testing, the number of TB isolation rooms, and other factors will depend on whether the risk for transmission of M. tuberculosis in the facility, area, or occupational group is high, intermediate, low, very low, or minimal.

* The risk assessment should be conducted by a qualified person or group of persons (e.g., hospital epidemiologists, infectious disease specialists, pulmonary disease specialists, infection-control practitioners, health-care administrators, occupational health personnel, engineers, HCWs, or local public health personnel).

* The risk assessment should be conducted for the entire facility and for specific areas within the facility (e.g., medical, TB, pulmonary, or HIV wards; HIV, infectious disease, or pulmonary clinics; and emergency departments or other areas where TB patients might receive care or where cough-inducing procedures are performed). This should include both inpatient and outpatient areas. In addition, risk assessments should be conducted for groups of HCWs who work throughout the facility rather than in a specific area (e.g., respiratory therapists; bronchoscopists; environmental services, dietary, and maintenance personnel; and students, interns, residents, and fellows).

TABLE 1. Elements of a risk assessment for tuberculosis (TB) in health-care facilities -----------------------------------------------------------------------------

1. Review the community TB profile (from public health department data).

2. Review the number of TB patients who were treated in each area of area of the facility (both inpatient and outpatient). (This information can be obtained by analyzing laboratory surveillance data and by reviewing discharge diagnoses or medical and infection-control records.)

3. Review the drug-susceptibility patterns of TB isolates of patients who were treated at the facility.

4. Analyze purified protein derivative (PPD)-tuberculin skin-test results of health-care workers (HCWs), by area or by occupational group for HCWs not assigned to a specific area (e.g., respiratory therapists).

5. To evaluate infection-control parameters, review medical records of a sample of TB patients seen at the facility.

Calculate intervals from:

* admission until TB suspected; * admission until TB evaluation performed; * admission until acid-fast bacilli (AFB) specimens ordered; * AFB specimens ordered until AFB specimens collected; * AFB specimens collected until AFB smears performed and reported; * AFB specimens collected until cultures performed and reported; * AFB specimens collected until species identification conducted and reported; * AFB specimens collected until drug-susceptibility tests performed and reported; * admission until TB isolation initiated; * admission until TB treatment initiated; and * duration of TB isolation.

Obtain the following additional information:

* Were appropriate criteria used for discontinuing isolation? * Did the patient have a history or prior admission to the facility * Was the TB treatment regimen adequate? * Were follow-up sputum specimens collected properly? * Was appropriate discharge planning conducted?

6. Perform an observational review of TB infection control practices.

7. Review the most recent environmental evaluation and maintenance procedures. ____________________________________________________________________________

  * Classification of risk for a facility, for a specific area, and for a specific occupational group should be based on a) the profile of TB in the community; b) the number of infectious TB patients admitted to the area or ward, or the estimated number of infectious TB patients to whom HCWs in an occupational group may be exposed; and c) the results of analysis of HCW PPD test conversions (where applicable) and possible person-to-person transmission of M. tuberculosis (Figure 1).

* All TB infection-control programs should include periodic reassessments of risk. The frequency of repeat risk assessments should be based on the results of the most recent risk assessment (Table 2, Figure 1).

* The "minimal-risk" category applies only to an entire facility. A "minimal-risk" facility does not admit TB patients to inpatient or outpatient areas and is not located in a community with TB (i.e., counties or communities in which TB cases have not been reported during the previous year). Thus, there is essentially no risk for exposure to TB patients in the facility. This category may also apply to many outpatient settings (e.g., many medical and dental offices).

* The "very low-risk" category generally applies only to an entire facility. A very low-risk facility is one in which a) patients with active TB are not admitted to inpatient areas but may receive initial assessment and diagnostic evaluation or outpatient management in outpatient areas (e.g., ambulatory-care and emergency departments) and b) patients who may have active TB and need inpatient care are promptly referred to a collaborating facility. In such facilities, the outpatient areas in which exposure to patients with active TB could occur should be assessed and assigned to the appropriate low-, intermediate-, or high-risk category. Categorical assignment will depend on the number of TB patients examined in the area during the preceding year and whether there is evidence of nosocomial transmission of M. tuberculosis in the area. If TB cases have been reported in the community, but no patients with active TB have been examined in the outpatient area during the preceding year, the area can be designated as very low risk (e.g., many medical offices).

The referring and receiving facilities should establish a referral agreement to prevent inappropriate management and potential loss to follow-up of patients suspected of having TB during evaluation in the triage system of a very low-risk facility.

In some facilities in which TB patients are admitted to inpatient areas, a very low-risk protocol may be appropriate for areas (e.g., administrative areas) or occupational groups that have only a very remote possibility of exposure to M. tuberculosis.

The very low-risk category may also be appropriate for outpatient facilities that do not provide initial assessment of persons who may have TB, but do screen patients for active TB as part of a limited medical screening before undertaking specialty care (e.g., dental settings).

* Low-risk" areas or occupational groups are those in which a) the PPD test conversion rate is not greater than that for areas or groups in which occupational exposure to M. tuberculosis is unlikely or than previous conversion rates for the same area or group, b) no clusters* of PPD test conversions have occurred, c) person-to-person transmission of M. tuberculosis has not been detected, and d) fewer than six TB patients are examined or treated per year.

__________ * Cluster: two or more PPD skin-test conversions occurring within a 3-month period among HCWs in a specific area or occupational group, and epidemiologic evidence suggests occupational (nosocomial) transmission.

* "Intermediate-risk" areas or occupational groups are those in which a) the PPD test conversion rate is not greater than that for areas or groups in which occupational exposure to M. tuberculosis is unlikely or than previous conversion rates for the same area or group, b) no clusters of PPD test conversions have occurred, c) person-to-person transmission of M. tuberculosis has not been detected, and d) six or more patients with active TB are examined or treated each year. Survey data suggest that facilities in which six or more TB patients are examined or treated each year may have an increased risk for transmission of M. tuberculosis (CDC, unpublished data); thus, areas in which six or more patients with active TB are examined or treated each year (or occupational groups in which HCWs are likely to be exposed to six or more TB patients per year) should be classified as "intermediate risk".

* "High-risk" areas or occupational groups are those in which a) the PPD test conversion rate is significantly greater than for areas or groups in which occupational exposure to M. tuberculosis is unlikely or than previous conversion rates for the same area or group, and epidemiologic evaluation suggests nosocomial transmission; or b) a cluster of PPD test conversions has occurred, and epidemiologic evaluation suggests nosocomial transmission of M. tuberculosis; or c) possible person-to-person transmission of M. tuberculosis has been detected.

* If no data or insufficient data for adequate determination of risk have been collected, such data should be compiled, analyzed, and reviewed expeditiously.

b. Community TB profile

* A profile of TB in the community that is served by the facility should be obtained from the public health department. This profile should include, at a minimum, the incidence (and prevalence, if available) of active TB in the community and the drug-susceptibility patterns of M. tuberculosis isolates (i.e., the antituberculous agents to which each isolate is susceptible and those to which it is resistant) from patients in the community.

c. Case surveillance

* Data concerning the number of suspected and confirmed active TB cases among patients and HCWs in the facility should be systematically collected, reviewed, and used to estimate the number of TB isolation rooms needed, to recognize possible clusters of nosocomial transmission, and to assess the level of potential occupational risk. The number of TB patients in specific areas of a facility can be obtained from laboratory surveillance data on specimens positive for AFB smears or M. tuberculosis cultures, from infection-control records, and from databases containing information about hospital discharge diagnoses.

* Drug-susceptibility patterns of M. tuberculosis isolates from TB patients treated in the facility should be reviewed to identify the frequency and patterns of drug resistance. This information may indicate a need to modify the initial treatment regimen or may suggest possible nosocomial transmission or increased occupational risk.

d. Analysis of HCW PPD test screening data

* Results of HCW PPD testing should be recorded in the individual HCW's employee health record and in a retrievable aggregate database of all HCW PPD test results. Personal identifying information should be handled confidentially. PPD test conversion rates should be calculated at appropriate intervals to estimate the risk for PPD test conversions for each area of the facility and for each specific occupational group not assigned to a specific area (Table 2). To calculate PPD test conversion rates, the total number of previously PPD-negative HCWs tested in each area or group (i.e., the denominator) and the number of PPD test conversions among HCWs in each area or group (the numerator) must be obtained.

* PPD test conversion rates for each area or occupational group should be compared with rates for areas or groups in which occupational exposure to M. tuberculosis is unlikely and with previous conversion rates in the same area or group to identify areas or groups where the risk for occupational PPD test conversions may be increased. A low number of HCWs in a specific area may result in a greatly increased rate of conversion for that area, although the actual risk may not be significantly greater than that for other areas. Testing for statistical significance (e.g., Fisher's exact test or chi square test) may assist interpretation; however, lack of statistical significance may not rule out a problem (i.e., if the number of HCWs tested is low, there may not be adequate statistical power to detect a significant difference). Thus, interpretation of individual situations is necessary.

* An epidemiologic investigation to evaluate the likelihood of nosocomial transmission should be conducted if PPD test conversions are noted (Section II.K.1).

* The frequency and comprehensiveness of the HCW PPD testing program should be evaluated periodically to ensure that all HCWs who should be included in the program are being tested at appropriate intervals. For surveillance purposes, earlier detection of transmission may be enhanced if HCWs in a given area or occupational group are tested on different scheduled dates rather than all being tested on the same date (Section II.J.3).

e. Review of TB patient medical records

* The medical records of a sample of TB patients examined at the facility can be reviewed periodically to evaluate infection-control parameters (Table 1). Parameters to examine may include the intervals from date of admission until a) TB was suspected, b) specimens for AFB smears were ordered, c) these specimens were collected, d) tests were performed, and e) results were reported. Moreover, the adequacy of the TB treatment regimens that were used should be evaluated.

* Medical record reviews should note previous hospital admissions of TB patients before the onset of TB symptoms. Patient-to-patient transmission may be suspected if active TB occurs in a patient who had a prior hospitalization during which exposure to another TB patient occurred or if isolates from two or more TB patients have identical characteristic drug-susceptibility or DNA fingerprint patterns.

* Data from the case review should be used to determine if there is a need to modify a) protocols for identifying and isolating patients who may have infectious TB, b) laboratory procedures, c) administrative policies and practices, or d) protocols for patient management.

f. Observation of TB infection-control practices

* Assessing adherence to the policies of the TB infection-control program should be part of the evaluation process. This assessment should be performed on a regular basis and whenever an increase occurs in the number of TB patients or HCW PPD test conversions. Areas at high risk for transmission of M. tuberculosis should be monitored more frequently than other areas. The review of patient medical records provides information on HCW adherence to some of the policies of the TB infection-control program. In addition, work practices related to TB isolation (e.g., keeping doors to isolation rooms closed) should be observed to determine if employers are enforcing, and HCWs are adhering to, these policies and if patient adherence is being enforced. If these policies are not being enforced or adhered to, appropriate education and other corrective action should be implemented.

g. Engineering evaluation

* Results of engineering maintenance measures should be reviewed at regular intervals (Table 3). Data from the most recent evaluation and from maintenance procedures and logs should be reviewed carefully as part of the risk assessment.

2. Development of the TB Infection-Control Plan

* Based on the results of the risk assessment, a written TB infection-control plan should be developed and implemented for each area of the facility and for each occupational group of HCWs not assigned to a specific area of the facility (Table 2; Table 3).

* The occurrence of drug-resistant TB in the facility or the community, or a relatively high prevalence of HIV infection among patients or HCWs in the community, may increase the concern about transmission of M. tuberculosis and may influence the decision regarding which protocol to follow (i.e., a higher-risk classification may be selected).

* Health-care facilities are likely to have a combination of low-, intermediate-, and high-risk areas or occupational groups during the same time period. The appropriate protocol should be implemented for each area or group.

* Areas in which cough-inducing procedures are performed on patients who may have active TB should, at the minimum, implement the intermediate-risk protocol.

3. Periodic Reassessment

* Follow-up risk assessment should be performed at the interval indicated by the most recent risk assessment (Figure 1; Table 2). Based on the results of the follow-up assessment, problem evaluation may need to be conducted or the protocol may need to be modified to a higher- or lower-risk level.

TABLE 3. Characteristics of an effective tuberculosis (TB) infection-control program*

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* A program such as this is appropriate for health-care facilities in which there is a high risk for transmission of Mycobacterium tuberculosis.

* After each risk assessment, the staff responsible for TB control, in conjunction with other appropriate HCWs, should review all TB control policies to ensure that they are effective and meet current needs.

4. Examples of Risk Assessment

Examples of six hypothetical situations and the means by which surveillance data are used to select a TB control protocol are described as follows:

Hospital A. The overall HCW PPD test conversion rate in the facility is 1.6%. No areas or HCW occupational groups have a significantly greater PPD test conversion rate than areas or groups in which occupational exposure to M. tuberculosis is unlikely (or than previous rates for the same area or group). No clusters of PPD test conversions have occurred. Patient-to-patient transmission has not been detected. Patients who have TB are admitted to the facility, but no area admits six or more TB patients per year. The low-risk protocol will be followed in all areas.

Hospital B. The overall HCW PPD test conversion rate in the facility is 1.8%. The PPD test conversion rate for the medical intensive-care unit rate is significantly higher than all other areas in the facility. The problem identification process is initiated (Section II.K). It is determined that all TB patients have been isolated appropriately. Other potential problems are then evaluated, and the cause for the higher rate is not identified. After consulting the public health department TB infection-control program, the high-risk protocol is followed in the unit until the PPD test conversion rate is similar to areas of the facility in which occupational exposure to TB patients is unlikely. If the rate remains significantly higher than other areas, further evaluation, including environmental and procedural studies, will be performed to identify possible reasons for the high conversion rate.

Hospital C. The overall HCW PPD test conversion rate in the facility is 2.4%. Rates range from 0 to 2.6% for the individual areas and occupational groups. None of these rates is significantly higher than rates for areas in which occupational exposure to M. tuberculosis is unlikely. No particular HCW group has higher conversion rates than the other groups. No clusters of HCW PPD test conversions have occurred. In two of the areas, HCWs cared for more than six TB patients during the preceding year. These two areas will follow the intermediate-risk protocol, and all other areas will follow the low-risk protocol. This hospital is located in the southeastern United States, and these conversion rates may reflect cross-reactivity with nontuberculous mycobacteria.

Hospital D. The overall HCW PPD test conversion rate in the facility is 1.2%. In no area did HCWs care for six or more TB patients during the preceding year. Three of the 20 respiratory therapists tested had PPD conversions, for a rate of 15%. The respiratory therapists who had PPD test conversions had spent all or part of their time in the pulmonary function laboratory, where induced sputum specimens were obtained. A low-risk protocol is maintained for all areas and occupational groups in the facility except for respiratory therapists. A problem evaluation is conducted in the pulmonary function laboratory (Section II.K). It is determined that the ventilation in this area is inadequate. Booths are installed for sputum induction. PPD testing and the risk assessment are repeated 3 months later. If the repeat testing at 3 months indicates that no more conversions have occurred, the respiratory therapists will return to the low-risk protocol.

Hospital E. Hospital E is located in a community that has a relatively low incidence of TB. To optimize TB services in the community, the four hospitals in the community have developed an agreement that one of them (e.g., Hospital G) will provide all inpatient services to persons who have suspected or confirmed TB. The other hospitals have implemented protocols in their ambulatory-care clinics and emergency departments to identify patients who may have active TB. These patients are then transferred to Hospital G for inpatient care if such care is considered necessary. After discharge from Hospital G, they receive follow-up care in the public health department's TB clinic. During the preceding year, Hospital E has identified fewer than six TB patients in its ambulatory-care and emergency departments and has had no PPD test conversions or other evidence of M. tuberculosis transmission among HCWs or patients in these areas. These areas are classified as low risk, and all other areas are classified as very low risk.

Hospital F. Hospital F is located in a county in which no TB cases have been reported during the preceding 2 years. A risk assessment conducted at the facility did not identify any patients who had suspected or confirmed TB during the preceding year. The facility is classified as minimal risk.

C. Identifying, Evaluating, and Initiating Treatment for Patients Who May Have Active TB

The most important factors in preventing transmission of M. tuberculosis are the early identification of patients who may have infectious TB, prompt implementation of TB precautions for such patients, and prompt initiation of effective treatment for those who are likely to have TB.

1. Identifying patients who may have active TB

* Health-care personnel who are assigned responsibility for TB infection control in ambulatory-care and inpatient settings should develop, implement, and enforce protocols for the early identification of patients who may have infectious TB.

* The criteria used in these protocols should be based on the prevalence and characteristics of TB in the population served by the specific facility. These protocols should be evaluated periodically and revised according to the results of the evaluation. Review of medical records of patients who were examined in the facility and diagnosed as having TB may serve as a guide for developing or revising these protocols.

* A diagnosis of TB may be considered for any patient who has a persistent cough (i.e., a cough lasting for greater than or equal to 3 weeks) or other signs or symptoms compatible with active TB (e.g., bloody sputum, night sweats, weight loss, anorexia, or fever). However, the index of suspicion for TB will vary in different geographic areas and will depend on the prevalence of TB and other characteristics of the population served by the facility. The index of suspicion for TB should be very high in geographic areas or among groups of patients in which the prevalence of TB is high (Section I.B). Appropriate diagnostic measures should be conducted and TB precautions implemented for patients in whom active TB is suspected.

2. Diagnostic evaluation for active TB

* Diagnostic measures for identifying TB should be conducted for patients in whom active TB is being considered. These measures include obtaining a medical history and performing a physical examination, PPD skin test, chest radiograph, and microscopic examination and culture of sputum or other appropriate specimens (6,34,35). Other diagnostic procedures (e.g., bronchoscopy or biopsy) may be indicated for some patients (36,37).

* Prompt laboratory results are crucial to the proper treatment of the TB patient and to early initiation of infection control. To ensure timely results, laboratories performing mycobacteriologic tests should be proficient at both the laboratory and administrative aspects of specimen processing. Laboratories should use the most rapid methods available (e.g., fluorescent microscopy for AFB smears; radiometric culture methods for isolation of mycobacteria; p-nitro-a-acetylamino-b-hydroxy-proprophenone [NAP] test, nucleic acid probes, or high-pressure liquid chromatography [HPLC] for species identification; and radiometric methods for drug-susceptibility testing). As other more rapid or sensitive tests become available, practical, and affordable, such tests should be incorporated promptly into the mycobacteriology laboratory. Laboratories that rarely receive specimens for mycobacteriologic analysis should refer the specimens to a laboratory that more frequently performs these tests.

* Results of AFB sputum smears should be available within 24 hours of specimen collection (38).

* The probability of TB is greater among patients who have positive PPD test results or a history of positive PPD test results, who have previously had TB or have been exposed to M. tuberculosis, or who belong to a group at high risk for TB (Section I.B). Active TB is strongly suggested if the diagnostic evaluation reveals AFB in sputum, a chest radiograph suggestive of TB, or symptoms highly suggestive of TB. TB can occur simultaneously in immunosuppressed persons who have pulmonary infections caused by other organisms (e.g., Pneumocystis carinii or Mycobacterium avium complex) and should be considered in the diagnostic evaluation of all patients who have symptoms compatible with TB (Suppl. 1; Suppl. 2).

* TB may be more difficult to diagnose among persons who have HIV infection (or other conditions associated with severe suppression of cell-mediated immunity) because of a nonclassical clinical or radiographic presentation and/or the simultaneous occurrence of other pulmonary infections (e.g., P. carinii pneumonia and M. avium complex). The difficulty in diagnosing TB in HIV-infected persons may be further compounded by impaired responses to PPD skin tests (39,40), the possibly lower sensitivity of sputum smears for detecting AFB (41), or the overgrowth of cultures with M. avium complex in specimens from patients infected with both M. avium complex and M. tuberculosis (42).

* Immunosuppressed patients who have pulmonary signs or symptoms that are ascribed initially to infections or conditions other than TB should be evaluated initially for coexisting TB. The evaluation for TB should be repeated if the patient does not respond to appropriate therapy for the presumed cause(s) of the pulmonary abnormalities (Suppl. 1; Suppl. 2).

* Patients with suspected or confirmed TB should be reported immediately to the appropriate public health department so that standard procedures for identifying and evaluating TB contacts can be initiated.

3. Initiation of treatment for suspected or confirmed TB

* Patients who have confirmed active TB or who are considered highly likely to have active TB should be started promptly on appropriate treatment in accordance with current guidelines (Suppl. 2)(43). In geographic areas or facilities that have a high prevalence of MDR-TB, the initial regimen used may need to be enhanced while the results of drug-susceptibility tests are pending. The decision should be based on analysis of surveillance data.

* While the patient is in the health-care facility, anti-TB drugs should be administered by directly observed therapy (DOT), the process by which an HCW observes the patient swallowing the medications. Continuing DOT after the patient is discharged should be strongly considered. This decision and the arrangements for providing outpatient DOT should be made in collaboration with the public health department.

D. Management of Patients Who May Have Active TB in Ambulatory-Care Settings and Emergency Departments

* Triage of patients in ambulatory-care settings and emergency departments should include vigorous efforts to promptly identify patients who have active TB. HCWs who are the first points of contact in facilities that serve populations at risk for TB should be trained to ask questions that will facilitate identification of patients with signs and symptoms suggestive of TB.

* Patients with signs or symptoms suggestive of TB should be evaluated promptly to minimize the amount of time they are in ambulatory-care areas. TB precautions should be followed while the diagnostic evaluation is being conducted for these patients.

* TB precautions in the ambulatory-care setting should include a) placing these patients in a separate area apart from other patients, and not in open waiting areas (ideally, in a room or enclosure meeting TB isolation requirements); b) giving these patients surgical masks* to wear and instructing them to keep their masks on; and c) giving these patients tissues and instructing them to cover their mouths and noses with the tissues when coughing or sneezing.

__________ * Surgical masks are designed to prevent the respiratory secretions of the person wearing the mask from entering the air. When not in a TB isolation room, patients suspected of having TB should wear surgical masks to reduce the expulsion of droplet nuclei into the air. These patients do not need to wear particulate respirators, which are designed to filter the air before it is inhaled by the person wearing the mask. Patients suspected of having or known to have TB should never wear a respirator that has an exhalation valve, because the device would provide no barrier to the expulsion of droplet nuclei into the air.

* TB precautions should be followed for patients who are known to have active TB and who have not completed therapy until a determination has been made that they are noninfectious (Suppl. 1).

* Patients with active TB who need to attend a health-care clinic should have appointments scheduled to avoid exposing HIV-infected or otherwise severely immunocompromised persons to M. tuberculosis. This recommendation could be accomplished by designating certain times of the day for appointments for these patients or by treating them in areas where immunocompromised persons are not treated.

* Ventilation in ambulatory-care areas where patients at high risk for TB are treated should be designed and maintained to reduce the risk for transmission of M. tuberculosis. General-use areas (e.g., waiting rooms) and special areas (e.g., treatment or TB isolation rooms in ambulatory areas) should be ventilated in the same manner as described for similar inpatient areas (Sections II.E.3, II.F; Suppl. 3). Enhanced general ventilation or the use of air-disinfection techniques (e.g., UVGI or recirculation of air within the room through high-efficiency particulate air [HEPA] filters) may be useful in general-use areas of facilities where many infectious TB patients receive care (Section II.F; Suppl. 3).

* Ideally, ambulatory-care settings in which patients with TB are frequently examined or treated should have a TB isolation room(s) available. Such rooms are not necessary in ambulatory-care settings in which patients who have confirmed or suspected TB are seen infrequently. However, these facilities should have a written protocol for early identification of patients with TB symptoms and referral to an area or a collaborating facility where the patient can be evaluated and managed appropriately. These protocols should be reviewed on a regular basis and revised as necessary. The additional guidelines in Section II.H should be followed in ambulatory-care settings where cough-inducing procedures are performed on patients who may have active TB.

E. Management of Hospitalized Patients Who Have Confirmed or Suspected TB

1. Initiation of isolation for TB

* In hospitals and other inpatient facilities, any patient suspected of having or known to have infectious TB should be placed in a TB isolation room that has currently recommended ventilation characteristics (Section II.E.3; Suppl. 3). Written policies for initiating isolation should specify a) the indications for isolation, b) the person(s) authorized to initiate and discontinue isolation, c) the isolation practices to follow, d) the monitoring of isolation, e) the management of patients who do not adhere to isolation practices, and f) the criteria for discontinuing isolation.

* In rare circumstances, placing more than one TB patient together in the same room may be acceptable. This practice is sometimes referred to as "cohorting" Because of the risk for patients becoming superinfected with drug-resistant organisms, patients with TB should be placed in the same room only if all patients involved a) have culture-confirmed TB, b) have drug-susceptibility test results available on a current specimen obtained during the present hospitalization, c) have identical drug-susceptibility patterns on these specimens, and d) are on effective therapy. Having isolates with identical DNA fingerprint patterns is not adequate evidence for placing two TB patients together in the same room, because isolates with the same DNA fingerprint pattern can have different drug-susceptibility patterns.

* Pediatric patients with suspected or confirmed TB should be evaluated for potential infectiousness according to the same criteria as are adults (i.e., on the basis of symptoms, sputum AFB smears, radiologic findings, and other criteria) (Suppl. 1). Children who may be infectious should be placed in isolation until they are determined to be noninfectious. Pediatric patients who may be infectious include those who have laryngeal or extensive pulmonary involvement, pronounced cough, positive sputum AFB smears, or cavitary TB or those for whom cough-inducing procedures are performed (44).

* The source of infection for a child with TB is often a member of the child's family (45). Therefore, parents and other visitors of all pediatric TB patients should be evaluated for TB as soon as possible. Until they have been evaluated, or the source case is identified, they should wear surgical masks when in areas of the facility outside of the child's room, and they should refrain from visiting common areas in the facility (e.g., the cafeteria or lounge areas).

* TB patients in intensive-care units should be treated the same as patients in noncritical-care settings. They should be placed in TB isolation and have respiratory secretions submitted for AFB smear and culture if they have undiagnosed pulmonary symptoms suggestive of TB.

* If readmitted to a health-care facility, patients who are known to have active TB and who have not completed therapy should have TB precautions applied until a determination has been made that they are noninfectious (Suppl. 1).

2. TB isolation practices

* Patients who are placed in TB isolation should be educated about the mechanisms of M. tuberculosis transmission and the reasons for their being placed in isolation. They should be taught to cover their mouths and noses with a tissue when coughing or sneezing, even while in the isolation room, to contain liquid drops and droplets before they are expelled into the air (46).

* Efforts should be made to facilitate patient adherence to isolation measures (e.g., staying in the TB isolation room). Such efforts might include the use of incentives (e.g., providing them with telephones, televisions, or radios in their rooms or allowing special dietary requests). Efforts should also be made to address other problems that could interfere with adherence to isolation (e.g., management of the patient's withdrawal from addictive substances [including tobacco]).

* Patients placed in isolation should remain in their isolation rooms with the door closed. If possible, diagnostic and treatment procedures should be performed in the isolation rooms to avoid transporting patients through other areas of the facility. If patients who may have infectious TB must be transported outside their isolation rooms for medically essential procedures that cannot be performed in the isolation rooms, they should wear surgical masks that cover their mouths and noses during transport. Persons transporting the patients do not need to wear respiratory protection outside the TB isolation rooms. Procedures for these patients should be scheduled at times when they can be performed rapidly and when waiting areas are less crowded.

* Treatment and procedure rooms in which patients who have infectious TB or who have an undiagnosed pulmonary disease and are at high risk for active TB receive care should meet the ventilation recommendations for isolation rooms (Section II.E.3; Suppl. 3). Ideally, facilities in which TB patients are frequently treated should have an area in the radiology department that is ventilated separately for TB patients. If this is not possible, TB patients should wear surgical masks and should stay in the radiology suite the minimum amount of time possible, then be returned promptly to their isolation rooms.

* The number of persons entering an isolation room should be minimal. All persons who enter an isolation room should wear respiratory protection (Section II.G; Suppl. 4). The patient's visitors should be given respirators to wear while in the isolation room, and they should be given general instructions on how to use their respirators.

* Disposable items contaminated with respiratory secretions are not associated with transmission of M. tuberculosis. However, for general infection-control purposes, these items should be handled and transported in a manner that reduces the risk for transmitting other microorganisms to patients, HCWs, and visitors and that decreases environmental contamination in the health-care facility. Such items should be disposed of in accordance with hospital policy and applicable regulations (Suppl. 5).

3. The TB isolation room

* TB isolation rooms should be single-patient rooms with special ventilation characteristics appropriate for the purposes of isolation (Suppl. 3). The primary purposes of TB isolation rooms are to a) separate patients who are likely to have infectious TB from other persons; b) provide an environment that will allow reduction of the concentration of droplet nuclei through various engineering methods; and c) prevent the escape of droplet nuclei from the TB isolation room and treatment room, thus preventing entry of M. tuberculosis into the corridor and other areas of the facility.

* To prevent the escape of droplet nuclei, the TB isolation room should be maintained under negative pressure (Suppl. 3). Doors to isolation rooms should be kept closed, except when patients or personnel must enter or exit the room, so that negative pressure can be maintained.

* Negative pressure in the room should be monitored daily while the room is being used for TB isolation.

* The American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (ASHRAE) (47), the American Institute of Architects (AIA) (48), and the Health Resources and Services Administration (49) recommend a minimum of 6 air changes per hour (ACH) for TB isolation and treatment rooms. This ventilation rate is based on comfort and odor control considerations. The effectiveness of this level of airflow in reducing the concentration of droplet nuclei in the room, thus reducing the transmission of airborne pathogens, has not been evaluated directly or adequately.

Ventilation rates of greater than 6 ACH are likely to produce an incrementally greater reduction in the concentration of bacteria in a room than are lower rates (50-52). However, accurate quantitation of decreases in risk that would result from specific increases in general ventilation levels has not been performed and may not be possible.

For the purposes of reducing the concentration of droplet nuclei, TB isolation and treatment rooms in existing health-care facilities should have an airflow of greater than or equal to 6 ACH. Where feasible, this airflow rate should be increased to greater than or equal to 12 ACH by adjusting or modifying the ventilation system or by using auxiliary means (e.g., recirculation of air through fixed HEPA filtration systems or portable air cleaners) (Suppl. 3, Section II.B.5.a) (53). New construction or renovation of existing health-care facilities should be designed so that TB isolation rooms achieve an airflow of greater than or equal to 12 ACH.

* Air from TB isolation rooms and treatment rooms used to treat patients who have known or suspected infectious TB should be exhausted to the outside in accordance with applicable federal, state, and local regulations. The air should not be recirculated into the general ventilation. In some instances, recirculation of air into the general ventilation system from such rooms is unavoidable (i.e., in existing facilities in which the ventilation system or facility configuration makes venting the exhaust to the outside impossible). In such cases, HEPA filters should be installed in the exhaust duct leading from the room to the general ventilation system to remove infectious organisms and particulates the size of droplet nuclei from the air before it is returned to the general ventilation system (Section II.F; Suppl. 3). Air from TB isolation and treatment rooms in new or renovated facilities should not be recirculated into the general ventilation system.

* Although not required, an anteroom may increase the effectiveness of the isolation room by minimizing the potential escape of droplet nuclei into the corridor when the door is opened. To work effectively, the anteroom should have positive air pressure in relation to the isolation room. The pressure relationship between the anteroom and the corridor may vary according to ventilation design.

* Upper-room air UVGI may be used as an adjunct to general ventilation in the isolation room (Section II.F; Suppl. 3). Air in the isolation room may be recirculated within the room through HEPA filters or UVGI devices to increase the effective ACH and to increase thermal efficiency.

* Health-care facilities should have enough isolation rooms to appropriately isolate all patients who have suspected or confirmed active TB. This number should be estimated using the results of the risk assessment of the health-care facility. Except for minimal- and very low-risk health-care facilities, all acute-care inpatient facilities should have at least one TB isolation room (Section II.B).

* Grouping isolation rooms together in one area of the facility may reduce the possibility of transmitting M. tuberculosis to other patients and may facilitate care of TB patients and the installation and maintenance of optimal engineering (particularly ventilation) controls.

4. Discontinuation of TB isolation

* TB isolation can be discontinued if the diagnosis of TB is ruled out. For some patients, TB can be ruled out when another diagnosis is confirmed. If a diagnosis of TB cannot be ruled out, the patient should remain in isolation until a determination has been made that the patient is noninfectious. However, patients can be discharged from the healthcare facility while still potentially infectious if appropriate postdischarge arrangements can be ensured (Section II.E.5).

* The length of time required for a TB patient to become noninfectious after starting anti-TB therapy varies considerably (Suppl. 1). Isolation should be discontinued only when the patient is on effective therapy, is improving clinically, and has had three consecutive negative sputum AFB smears collected on different days.

* Hospitalized patients who have active TB should be monitored for relapse by having sputum AFB smears examined regularly (e.g., every 2 weeks). Nonadherence to therapy (i.e., failure to take medications as prescribed) and the presence of drug-resistant organisms are the two most common reasons why patients remain infectious despite treatment. These reasons should be considered if a patient does not respond clinically to therapy within 2-3 weeks.

* Continued isolation throughout the hospitalization should be strongly considered for patients who have MDR-TB because of the tendency for treatment failure or relapse (i.e., difficulty in maintaining noninfectiousness) that has been observed in such cases.

5. Discharge planning

* Before a TB patient is discharged from the health-care facility, the facility's staff and public health authorities should collaborate to ensure continuation of therapy. Discharge planning in the health-care facility should include, at a minimum, a) a confirmed outpatient appointment with the provider who will manage the patient until the patient is cured, b) sufficient medication to take until the outpatient appointment, and c) placement into case management (e.g., DOT) or outreach programs of the public health department. These plans should be initiated and in place before the patient's discharge.

* Patients who may be infectious at the time of discharge should only be discharged to facilities that have isolation capability or to their homes. Plans for discharging a patient who will return home must consider whether all the household members were infected previously and whether any uninfected household members are at very high risk for active TB if infected (e.g., children less than 4 years of age or persons infected with HIV or otherwise severely immunocompromised). If the household does include such persons, arrangements should be made to prevent them from being exposed to the TB patient until a determination has been made that the patient is noninfectious.

F. Engineering Control Recommendations

1. General ventilation

This section deals only with engineering controls for general-use areas of health-care facilities (e.g., waiting-room areas and emergency departments). Recommendations for engineering controls for specific areas of the facility (e.g., TB isolation rooms) are contained in the sections encompassing those areas. Details regarding ventilation design, evaluation, and supplemental approaches are described in Supplement 3.

* Health-care facilities should either a) include as part of their staff an engineer or other professional with expertise in ventilation or b) have this expertise available from a consultant who is an expert in ventilation engineering and who also has hospital experience. These persons should work closely with infection-control staff to assist in controlling airborne infections.

* Ventilation system designs in health-care facilities should meet any applicable federal, state, and local requirements.

* The direction of airflow in health-care facilities should be designed, constructed, and maintained so that air flows from clean areas to less-clean areas.

* Health-care facilities serving populations that have a high prevalence of TB may need to supplement the general ventilation or use additional engineering approaches (i.e., HEPA filtration or UVGI) in general-use areas where TB patients are likely to go (e.g., waiting-room areas, emergency departments, and radiology suites). A single-pass, nonrecirculating system that exhausts air to the outside, a recirculation system that passes air through HEPA filters before recirculating it to the general ventilation system, or upper air UVGI may be used in such areas.

2. Additional engineering control approaches

a. HEPA filtration

HEPA filters may be used in a number of ways to reduce or eliminate infectious droplet nuclei from room air or exhaust (Suppl. 3). These methods include placement of HEPA filters a) in exhaust ducts discharging air from booths or enclosures into the surrounding room; b) in ducts or in ceiling- or wall-mounted units, for recirculation of air within an individual room (fixed recirculation systems); c) in portable air cleaners; d) in exhaust ducts to remove droplet nuclei from air being discharged to the outside, either directly or through ventilation equipment; and e) in ducts discharging air from the TB isolation room into the general ventilation system. In any application, HEPA filters should be installed carefully and maintained meticulously to ensure adequate functioning.

The manufacturers of in-room air cleaning equipment should provide documentation of the HEPA filter efficiency and the efficiency of the device in lowering room air contaminant levels.

b. UVGI

For general-use areas in which the risk for transmission of M. tuberculosis is relatively high, UVGI lamps may be used as an adjunct to ventilation for reducing the concentration of infectious droplet nuclei (Suppl. 3), although the effectiveness of such units has not been evaluated adequately. Ultra-violet (UV) units can be installed in a room or corridor to irradiate the air in the upper portion of the room (i.e., upper-room air irradiation), or they can be installed in ducts to irradiate air passing through the ducts. UV units installed in ducts should not be substituted for HEPA filters in ducts that discharge air from TB isolation rooms into the general ventilation system. However, UV units can be used in ducts that recirculate air back into the same room.

To function properly and decrease hazards to HCWs and others in the health-care facility, UV lamps should be installed properly and maintained adequately, which includes the monitoring of irradiance levels. UV tubes should be changed according to the manufacturer's instructions or when meter readings indicate tube failure. An employee trained in the use and handling of UV lamps should be responsible for these measures and for keeping maintenance records. Applicable safety guidelines should be followed. Caution should be exercised to protect HCWs, patients, visitors, and others from excessive exposure to UV radiation.

G. Respiratory Protection

* Personal respiratory protection should be used by a) persons entering rooms in which patients with known or suspected infectious TB are being isolated, b) persons present during cough-inducing or aerosol-generating procedures performed on such patients, and c) persons in other settings where administrative and engineering controls are not likely to protect them from inhaling infectious airborne droplet nuclei (Suppl. 4). These other settings include transporting patients who may have infectious TB in emergency transport vehicles and providing urgent surgical or dental care to patients who may have infectious TB before a determination has been made that the patient is noninfectious (Suppl. 1).

* Respiratory protective devices used in health-care settings for protection against M. tuberculosis should meet the following standard performance criteria:

1. The ability to filter particles 1 um in size in the unloaded* state with a filter efficiency of greater than or equal to 95% (i.e., filter leakage of less than or equal to 5%), given flow rates of up to 50 L per minute.

__________ * Some filters become more efficient as they become loaded with dust. Health-care settings do not have enough dust in the air to load a filter on a respirator. Therefore, the filter efficiency for respirators used in health-care settings must be determined in the unloaded state.

2. The ability to be qualitatively or quantitatively fit tested in a reliable way to obtain a face-seal leakage of less than or equal to 10% (54,55).

3. The ability to fit the different facial sizes and characteristics of HCWs, which can usually be met by making the respirators available in at least three sizes.

4. The ability to be checked for facepiece fit, in accordance with standards established by the Occupational Safety and Health Administration (OSHA) and good industrial hygiene practice, by HCWs each time they put on their respirators (54,55).

* The facility's risk assessment may identify a limited number of selected settings (e.g., bronchoscopy performed on patients suspected of having TB or autopsy performed on deceased persons suspected of having had active TB at the time of death) where the estimated risk for transmission of M. tuberculosis may be such that a level of respiratory protection exceeding the standard performance criteria is appropriate. In such circumstances, a level of respiratory protection exceeding the standard criteria and compatible with patient-care delivery (e.g., more protective negative-pressure respirators; powered air-purifying particulate respirators [PAPRs]; or positive-pressure air-line, half-mask respirators) should be provided by employers to HCWs who are exposed to M. tuberculosis. Information on these and other respirators is in the NIOSH Guide to Industrial Respiratory Protection (55) and in Supplement 4 of this document.

* In some settings, HCWs may be at risk for two types of exposure: a) inhalation of M. tuberculosis and b) mucous membrane exposure to fluids that may contain bloodborne pathogens. In these settings, protection against both types of exposure should be used.

* When operative procedures (or other procedures requiring a sterile field) are performed on patients who may have infectious TB, respiratory protection worn by the HCW should serve two functions: a) it should protect the surgical field from the respiratory secretions of the HCW, and b) it should protect the HCW from infectious droplet nuclei that may be expelled by the patient or generated by the procedure. Respirators with exhalation valves and most positive-pressure respirators do not protect the sterile field.

* Health-care facilities in which respiratory protection is used to prevent inhalation of M. tuberculosis are required by OSHA to develop, implement, and maintain a respiratory protection program (Suppl. 4). All HCWs who use respiratory protection should be included in this program. Visitors to TB patients should be given respirators to wear while in isolation rooms, and they should be given general instructions on how to use their respirators.

* Facilities that do not have isolation rooms and do not perform cough-inducing procedures on patients who may have TB may not need to have a respiratory protection program for TB. However, such facilities should have written protocols for the early identification of patients who have signs or symptoms of TB and procedures for referring these patients to a facility where they can be evaluated and managed appropriately. These protocols should be evaluated regularly and revised as needed.

* Surgical masks are designed to prevent the respiratory secretions of the person wearing the mask from entering the air. To reduce the expulsion of droplet nuclei into the air, patients suspected of having TB should wear surgical masks when not in TB isolation rooms. These patients do not need to wear particulate respirators, which are designed to filter the air before it is inhaled by the person wearing the respirator. Patients suspected of having or known to have TB should never wear a respirator that has an exhalation valve, because this type of respirator does not prevent expulsion of droplet nuclei into the air.

H. Cough-Inducing and Aerosol-Generating Procedures

1. General guidelines

Procedures that involve instrumentation of the lower respiratory tract or induce coughing can increase the likelihood of droplet nuclei being expelled into the air. These cough-inducing procedures include endotracheal intubation and suctioning, diagnostic sputum induction, aerosol treatments (e.g., pentamidine therapy), and bronchoscopy. Other procedures that can generate aerosols (e.g., irrigation of tuberculous abscesses, homogenizing or lyophilizing tissue, or other processing of tissue that may contain tubercle bacilli) are also covered by these recommendations.

* Cough-inducing procedures should not be performed on patients who may have infectious TB unless the procedures are absolutely necessary and can be performed with appropriate precautions.

* All cough-inducing procedures performed on patients who may have infectious TB should be performed using local exhaust ventilation devices (e.g., booths or special enclosures) or, if this is not feasible, in a room that meets the ventilation requirements for TB isolation.

* HCWs should wear respiratory protection when present in rooms or enclosures in which cough-inducing procedures are being performed on patients who may have infectious TB.

* After completion of cough-inducing procedures, patients who may have infectious TB should remain in their isolation rooms or enclosures and not return to common waiting areas until coughing subsides. They should be given tissues and instructed to cover their mouths and noses with the tissues when coughing. If TB patients must recover from sedatives or anesthesia after a procedure (e.g, after a bronchoscopy), they should be placed in separate isolation rooms (and not in recovery rooms with other patients) while they are being monitored.

* Before the booth, enclosure, or room is used for another patient, enough time should be allowed to pass for at least 99% of airborne contaminants to be removed. This time will vary according to the efficiency of the ventilation or filtration used (Suppl. 3, Table S-31).

2. Special considerations for bronchoscopy

* If performing bronchoscopy in positive-pressure rooms (e.g., operating rooms) is unavoidable, TB should be ruled out as a diagnosis before the procedure is performed. If the bronchoscopy is being performed for the purpose of diagnosing pulmonary disease and that diagnosis could include TB, the procedure should be performed in a room that meets TB isolation ventilation requirements.

3. Special considerations for the administration of aerosolized pentamidine

* Patients should be screened for active TB before prophylactic therapy with aerosolized pentamidine is initiated. Screening should include obtaining a medical history and performing skin testing and chest radiography.

* Before each subsequent treatment with aerosolized pentamidine, patients should be screened for symptoms suggestive of TB (e.g., development of a productive cough). If such symptoms are elicited, a diagnostic evaluation for TB should be initiated.

* Patients who have suspected or confirmed active TB should take, if clinically practical, oral prophylaxis for P. carinii pneumonia.

I. Education and Training of HCWs

All HCWs, including physicians, should receive education regarding TB that is relevant to persons in their particular occupational group. Ideally, training should be conducted before initial assignment, and the need for additional training should be reevaluated periodically (e.g., once a year). The level and detail of this education will vary according to the HCW's work responsibilities and the level of risk in the facility (or area of the facility) in which the HCW works. However, the program may include the following elements:

* The basic concepts of M. tuberculosis transmission, pathogenesis, and diagnosis, including information concerning the difference between latent TB infection and active TB disease, the signs and symptoms of TB, and the possibility of reinfection.

* The potential for occupational exposure to persons who have infectious TB in the health-care facility, including information concerning the prevalence of TB in the community and facility, the ability of the facility to properly isolate patients who have active TB, and situations with increased risk for exposure to M. tuberculosis.

* The principles and practices of infection control that reduce the risk for transmission of M. tuberculosis, including information concerning the hierarchy of TB infection-control measures and the written policies and procedures of the facility. Site-specific control measures should be provided to HCWs working in areas that require control measures in addition to those of the basic TB infection-control program.

* The purpose of PPD skin testing, the significance of a positive PPD test result, and the importance of participating in the skin-test program.

* The principles of preventive therapy for latent TB infection. These principles include the indications, use, effectiveness, and the potential adverse effects of the drugs (Suppl. 2).

* The HCW's responsibility to seek prompt medical evaluation if a PPD test conversion occurs or if symptoms develop that could be caused by TB. Medical evaluation will enable HCWs who have TB to receive appropriate therapy and will help to prevent transmission of M. tuberculosis to patients and other HCWs.

* The principles of drug therapy for active TB.

* The importance of notifying the facility if the HCW is diagnosed with active TB so that contact investigation procedures can be initiated.

* The responsibilities of the facility to maintain the confidentiality of the HCW while ensuring that the HCW who has TB receives appropriate therapy and is noninfectious before returning to duty.

* The higher risks associated with TB infection in persons who have HIV infection or other causes of severely impaired cell-mediated immunity, including a) the more frequent and rapid development of clinical TB after infection with M. tuberculosis, b) the differences in the clinical presentation of disease, and c) the high mortality rate associated with MDR-TB in such persons.

* The potential development of cutaneous anergy as immune function (as measured by CD4+ T-lymphocyte counts) declines.

* Information regarding the efficacy and safety of BCG vaccination and the principles of PPD screening among BCG recipients.

* The facility's policy on voluntary work reassignment options for immunocompromised HCWs.

J. HCW Counseling, Screening, and Evaluation

* A TB counseling, screening, and prevention program for HCWs should be established to protect both HCWs and patients. HCWs who have positive PPD test results, PPD test conversions, or symptoms suggestive of TB should be identified, evaluated to rule out a diagnosis of active TB, and started on therapy or preventive therapy if indicated (5). In addition, the results of the HCW PPD screening program will contribute to evaluation of the effectiveness of current infection-control practices.

1. Counseling HCWs regarding TB

* Because of the increased risk for rapid progression from latent TB infection to active TB in HIV-infected or otherwise severely immunocompromised persons, all HCWs should know if they have a medical condition or are receiving a medical treatment that may lead to severely impaired cell-mediated immunity. HCWs who may be at risk for HIV infection should know their HIV status (i.e., they should be encouraged to voluntarily seek counseling and testing for HIV antibody status). Existing guidelines for counseling and testing should be followed routinely (56). Knowledge of these conditions allows the HCW to seek the appropriate preventive measures outlined in this document and to consider voluntary work reassignments. Of particular importance is that HCWs need to know their HIV status if they are at risk for HIV infection and they work in settings where patients who have drug-resistant TB may be encountered.

* All HCWs should be informed about the need to follow existing recommendations for infection control to minimize the risk for exposure to infectious agents; implementation of these recommendations will greatly reduce the risk for occupational infections among HCWs (57). All HCWs should also be informed about the potential risks to severely immunocompromised persons associated with caring for patients who have some infectious diseases, including TB. It should be emphasized that limiting exposure to TB patients is the most protective measure that severely immunosuppressed HCWs can take to avoid becoming infected with M. tuberculosis. HCWs who have severely impaired cell-mediated immunity and who may be exposed to M. tuberculosis may consider a change in job setting to avoid such exposure. HCWs should be advised of the option that severely immunocompromised HCWs can choose to transfer voluntarily to areas and work activities in which there is the lowest possible risk for exposure to M. tuberculosis. This choice should be a personal decision for HCWs after they have been informed of the risks to their health.

* Employers should make reasonable accommodations (e.g., alternative job assignments) for employees who have a health condition that compromises cell-mediated immunity and who work in settings where they may be exposed to M. tuberculosis. HCWs who are known to be immunocompromised should be referred to employee health professionals who can individually counsel the employees regarding their risk for TB. Upon the request of the immunocompromised HCW, employers should offer, but not compel, a work setting in which the HCW would have the lowest possible risk for occupational exposure to M. tuberculosis. Evaluation of these situations should also include consideration of the provisions of the Americans With Disabilities Act of 1990* and other applicable federal, state, and local laws.

__________ * Americans With Disabilities Act of 1990. PL 101-336, 42 U.S.C. 12101 et seq.

* All HCWs should be informed that immunosuppressed HCWs should have appropriate follow-up and screening for infectious diseases, including TB, provided by their medical practitioner. HCWs who are known to be HIV-infected or otherwise severely immunosuppressed should be tested for cutaneous anergy at the time of PPD testing (Suppl. 2). Consideration should be given to retesting, at least every 6 months, those immunocompromised HCWs who are potentially exposed to M. tuberculosis because of the high risk for rapid progression to active TB if they become infected.

* Information provided by HCWs regarding their immune status should be treated confidentially. If the HCW requests voluntary job reassignment, the confidentiality of the HCW should be maintained. Facilities should have written procedures on confidential handling of such information.

2. Screening HCWs for active TB

* Any HCW who has a persistent cough (i.e., a cough lasting greater than or equal to 3 weeks), especially in the presence of other signs or symptoms compatible with active TB (e.g., weight loss, night sweats, bloody sputum, anorexia, or fever), should be evaluated promptly for TB. The HCW should not return to the workplace until a diagnosis of TB has been excluded or until the HCW is on therapy and a determination has been made that the HCW is noninfectious.

3. Screening HCWs for latent TB infection

* The risk assessment should identify which HCWs have potential for exposure to M. tuberculosis and the frequency with which the exposure may occur. This information is used to determine which HCWs to include in the skin-testing program and the frequency with which they should be Table 2).

* If HCWs are from risks groups with increased prevalence of TB, consideration may be given to including them in the skin-testing program, even if they do not have potential occupational exposure to M. tuberculosis, so that converters can be identified and preventive therapy offered.

* Administrators of health-care facilities should ensure that physicians and other personnel not paid by, but working in, the facility receive skin testing at appropriate intervals for their occupational group and work location.

* During the pre-employment physical or when applying for hospital privileges, HCWs who have potential for exposure to M. tuberculosis (Table 2), including those with a history of BCG vaccination, should have baseline PPD skin testing performed (Suppl. 2). For HCWs who have not had a documented negative PPD test result during the preceding 12 months, the baseline PPD testing should employ the two-step method; this will detect boosting phenomena that might be misinterpreted as a skin-test conversion. Decisions concerning the use of the two-step procedure for baseline testing in a particular facility should be based on the frequency of boosting in that facility.

* HCWs who have a documented history of a positive PPD test, adequate treatment for disease, or adequate preventive therapy for infection, should be exempt from further PPD screening unless they develop signs or symptoms suggestive of TB.

* PPD-negative HCWs should undergo repeat PPD testing at regular intervals as determined by the risk assessment (Section II.B). In addition, these HCWs should be tested whenever they have been exposed to a TB patient and appropriate precautions were not observed at the time of exposure (Section II.K.3). Performing PPD testing of HCWs who work in the same area or occupational group on different scheduled dates (e.g., test them on their birthdays or on their employment anniversary dates), rather than testing all HCWs in the area or group on the same day, may lead to earlier detection of M. tuberculosis transmission.

* All PPD tests should be administered, read, and interpreted in accordance with current guidelines by specified trained personnel (Suppl. 2). At the time their test results are read, HCWs should be informed about the interpretation of both positive and negative PPD test results. This information should indicate that the interpretation of an induration that is 5-9 mm in diameter depends on the HCW's immune status and history of exposure to persons who have infectious TB. Specifically, HCWs who have indurations of 5-9 mm in diameter should be advised that such results may be considered positive for HCWs who are contacts of persons with infectious TB or who have HIV infection or other causes of severe immunosuppression (e.g., immunosuppressive therapy for organ transplantation).

* When an HCW who is not assigned regularly to a single work area has a PPD test conversion, appropriate personnel should identify the areas where the HCW worked during the time when infection was likely to have occurred. This information can then be considered in analyzing the risk for transmission in those areas.

* In any area of the facility where transmission of M. tuberculosis is known to have occurred, a problem evaluation should be conducted (Section II.K), and the frequency of skin testing should be determined according to the applicable risk category (Section II.B).

* PPD test results should be recorded confidentially in the individual HCW's employee health record and in an aggregate database of all HCW PPD test results. The database can be analyzed periodically to estimate the risk for acquiring new infection in specific areas or occupational groups in the facility.

4. Evaluation and management of HCWs who have positive PPD test results or active TB

a. Evaluation

* All HCWs with newly recognized positive PPD test results or PPD test conversions should be evaluated promptly for active TB. This evaluation should include a clinical examination and a chest radiograph. If the history, clinical examination, or chest radiograph is compatible with active TB, additional tests should be performed (Section II.C.2). If symptoms compatible with TB are present, the HCW should be excluded from the workplace until either a) a diagnosis of active TB is ruled out or b) a diagnosis of active TB was established, the HCW is being treated, and a determination has been made that the HCW is noninfectious (Suppl. 2). HCWs who do not have active TB should be evaluated for preventive therapy according to published guidelines (Suppl. 2).

* If an HCW's PPD test result converts to positive, a history of confirmed or suspected TB exposure should be obtained in an attempt to determine the potential source. When the source of exposure is known, the drug-susceptibility pattern of the M. tuberculosis isolated from the source should be identified so that the correct curative or preventive therapy can be initiated for the HCW with the PPD test conversion. The drug-susceptibility pattern should be recorded in the HCW's medical record, where it will be available if the HCW subsequently develops active TB and needs therapy specific for the drug-susceptibility pattern.

* All HCWs, including those with histories of positive PPD test results, should be reminded periodically about the symptoms of TB and the need for prompt evaluation of any pulmonary symptoms suggestive of TB.

b. Routine and follow-up chest radiographs

* Routine chest radiographs are not required for asymptomatic, PPD-negative HCWs. HCWs with positive PPD test results should have a chest radiograph as part of the initial evaluation of their PPD test; if negative, repeat chest radiographs are not needed unless symptoms develop that could be attributed to TB (58). However, more frequent monitoring for symptoms of TB may be considered for recent converters and other PPD-positive HCWs who are at increased risk for developing active TB (e.g., HIV-infected or otherwise severely immunocompromised HCWs).

c. Workplace restrictions

1) Active TB

* HCWs with pulmonary or laryngeal TB pose a risk to patients and other HCWs while they are infectious, and they should be excluded from the workplace until they are noninfectious. The same work restrictions apply to all HCWs regardless of their immune status.

* Before the HCW who has TB can return to the work-place, the health-care facility should have documentation from the HCW's health-care provider that the HCW is receiving adequate therapy, the cough has resolved, and the HCW has had three consecutive negative sputum smears collected on different days. After work duties are resumed and while the HCW remains on anti-TB therapy, facility staff should receive periodic documentation from the HCW's health-care provider that the HCW is being maintained on effective drug therapy for the recommended time period and that the sputum AFB smears continue to be negative.

* HCWs with active laryngeal or pulmonary TB who discontinue treatment before they are cured should be evaluated promptly for infectiousness. If the evaluation determines that they are still infectious, they should be excluded from the workplace until treatment has been resumed, an adequate response to therapy has been documented, and three more consecutive sputum AFB smears collected on different days have been negative.

* HCWs who have TB at sites other than the lung or larynx usually do not need to be excluded from the workplace if a diagnosis of concurrent pulmonary TB has been ruled out.

2) Latent TB infection

* HCWs receiving preventive treatment for latent TB infection should not be restricted from their usual work activities.

* HCWs with latent TB infection who cannot take or who do not accept or complete a full course of preventive therapy should not be excluded from the work-place. These HCWs should be counseled about the risk for developing active TB and instructed regularly to seek prompt evaluation if signs or symptoms develop that could be caused by TB.

K. Problem Evaluation

Epidemiologic investigations may be indicated for several situations. These include, but are not limited to, a) the occurrence of PPD test conversions or active TB in HCWs; b) the occurrence of possible person-to-person transmission of M. tuberculosis; and c) situations in which patients or HCWs with active TB are not promptly identified and isolated, thus exposing other persons in the facility to M. tuberculosis. The general objectives of the epidemiologic investigations in these situations are as follows:

1) to determine the likelihood that transmission of and infection with M. tuberculosis has occurred in the facility;

2) to determine the extent to which M. tuberculosis has been transmitted;

3) to identify those persons who have been exposed and infected, enabling them to receive appropriate clinical management;

4) to identify factors that could have contributed to transmission and infection and to implement appropriate interventions; and

5) to evaluate the effectiveness of any interventions that are implemented and to ensure that exposure to and transmission of M. tuberculosis have been terminated.

The exact circumstances of these situations are likely to vary considerably, and the associated epidemiologic investigations should be tailored to the individual circumstances. The following sections provide general guidance for conducting these investigations.

1. Investigating PPD test conversions and active TB in HCWs

a. Investigating PPD test conversions in HCWs

PPD test conversions may be detected in HCWs as a result of a contact investigation, in which case the probable source of exposure and transmission is already known (Section II.K.3.), or as a result of routine screening, in which case the probable source of exposure and infection is not already known and may not be immediately apparent.

If a skin-test conversion in an HCW is identified as part of routine screening, the following steps should be considered (Figure 2):

* The HCW should be evaluated promptly for active TB. The initial evaluation should include a thorough history, physical examination, and chest radiograph. On the basis of the initial evaluation, other diagnostic procedures (e.g., sputum examination) may be indicated.

* If appropriate, the HCW should be placed on preventive or curative therapy in accordance with current guidelines (Suppl. 2) (5).

* A history of possible exposure to M. tuberculosis should be obtained from the HCW to determine the most likely source of infection. When the source of infection is known, the drug-susceptibility pattern of the M. tuberculosis isolate from the source patient should be identified to determine appropriate preventive or curative therapy regimens.

* If the history suggests that the HCW was exposed to and infected with M. tuberculosis outside the facility, no further epidemiologic investigation to identify a source in the facility is necessary.

* If the history does not suggest that the HCW was exposed and infected outside the facility but does identify a probable source of exposure in the facility, contacts of the suspected source patient should be identified and evaluated. Possible reasons for the exposure and transmission should be evaluated (Table 4), interventions should be implemented to correct these causes, and PPD testing of PPD-negative HCWs should be performed immediately and repeated after 3 months.

If no additional PPD test conversions are detected on follow-up testing, the investigation can be terminated.

If additional PPD test conversions are detected on follow-up testing, the possible reasons for exposure and transmission should be reassessed, the appropriateness of and degree of adherence to the interventions implemented should be evaluated, and PPD testing of PPD-negative HCWs should be repeated after another 3 months.

If no additional PPD test conversions are detected on the second round of follow-up testing, the investigation can be terminated. However, if additional PPD conversions are detected on the second round of follow-up testing, a high-risk protocol should be implemented in the affected area or occupational group, and the public health department or other persons with expertise in TB infection control should be consulted.

* If the history does not suggest that the HCW was exposed to and infected with M. tuberculosis outside the facility and does not identify a probable source of exposure in the facility, further investigation to identify the probable source patient in the facility is warranted.

The interval during which the HCW could have been infected should be estimated. Generally, this would be the interval from 10 weeks before the most recent negative PPD test through 2 weeks before the first positive PPD test (i.e., the conversion).

Laboratory and infection-control records should be reviewed to identify all patients or HCWs who have suspected or confirmed infectious TB and who could have transmitted M. tuberculosis to the HCW.

If this process does identify a likely source patient, contacts of the suspected source patient should be identified and evaluated, and possible reasons for the exposure and transmission should be evaluated (Table 4). Interventions should be implemented to correct these causes, and PPD testing of PPD-negative HCWs should be repeated after 3 months. However, if this process does not identify a probable source case, PPD screening results of other HCWs in the same area or occupational group should be reviewed for additional evidence of M. tuberculosis transmission. If sufficient additional PPD screening results are not available, appropriate personnel should consider conducting additional PPD screening of other HCWs in the same area or occupational group.

If this review and/or screening does not identify additional PPD conversions, nosocomial transmission is less likely, and the contact investigation can probably be terminated. Whether the HCW's PPD test conversion resulted from occupational exposure and infection is uncertain; however, the absence of other data implicating nosocomial transmission suggests that the conversion could have resulted from a) unrecognized exposure to M. tuberculosis outside the facility; b) cross-reactivity with another antigen (e.g., nontuberculous mycobacteria); c) errors in applying, reading, or interpreting the test; d) false positivity caused by the normal variability of the test; or e) false positivity caused by a defective PPD preparation.

If this review and/or screening does identify additional PPD test conversions, nosocomial transmission is more likely. In this situation, the patient identification (i.e., triage) process, TB infection-control policies and practices, and engineering controls should be evaluated to identify problems that could have led to exposure and transmission (Table 4).

If no such problems are identified, a high-risk protocol should be implemented in the affected area or occupational group, and the public health department or other persons with expertise in TB infection control should be consulted.

If such problems are identified, appropriate interventions should be implemented to correct the problem(s), and PPD skin testing of PPD-negative HCWs should be repeated after 3 months.

If no additional PPD conversions are detected on follow-up testing, the investigation can be terminated.

If additional PPD conversions are detected on follow-up testing, the possible reasons for exposure and transmission should be reassessed, the appropriateness of and adherence to the interventions implemented should be evaluated, and PPD skin testing of PPD-negative HCWs should be repeated after another 3 months.

If no additional PPD test conversions are detected on this second round of follow-up testing, the investigation can be terminated. However, if additional PPD test conversions are detected on the second round of follow-up testing, a high-risk protocol should be implemented in the affected area or occupational group, and the public health department or other persons with expertise in TB infection control should be consulted.

b. Investigating cases of active TB in HCWs

If an HCW develops active TB, the following steps should be taken:

* The case should be evaluated epidemiologically, in a manner similar to PPD test conversions in HCWs, to determine the likelihood that it resulted from occupational transmission and to identify possible causes and implement appropriate interventions if the evaluation suggests such transmission.

* Contacts of the HCW (e.g., other HCWs, patients, visitors, and others who have had intense exposure to the HCW) should be identified and evaluated for TB infection and disease (Section II.K.3; Suppl. 2). The public health department should be notified immediately for consultation and to allow for investigation of community contacts who were not exposed in the health-care facility.

* The public health department should notify facilities when HCWs with TB are reported by physicians so that an investigation of contacts can be conducted in the facility. The information provided by the health department to facilities should be in accordance with state or local laws to protect the confidentiality of the HCW.

2. Investigating possible patient-to-patient transmission of M. tuberculosis

Surveillance of active TB cases in patients should be conducted. If this surveillance suggests the possibility of patient-to-patient transmission of M. tuberculosis (e.g., a high proportion of TB patients had prior admissions during the year preceding onset of their TB, the number of patients with drug-resistant TB increased suddenly, or isolates obtained from multiple patients had identical and characteristic drug-susceptibility or DNA fingerprint patterns), the following steps should be taken:

* Review the HCW PPD test results and patient surveillance data for the suspected areas to detect additional patients or HCWs with PPD test conversions or active disease.

* Look for possible exposures that patients with newly diagnosed TB could have had to other TB patients during previous admissions. For example, were the patients admitted to the same room or area, or did they receive the same procedure or go to the same treatment area on the same day?

If the evaluation thus far suggests transmission has occurred, the following steps should be taken:

* Evaluate possible causes of the transmission (e.g., problem with patient detection, institutional barriers to implementing appropriate isolation practices, or inadequate engineering controls) (Table 4).

* Ascertain whether other patients or HCWs could have been exposed; if so, evaluate these persons for TB infection and disease (Section II.K.3; Suppl. 2).

* Notify the public health department so they can begin a community contact investigation if necessary.

3. Investigating contacts of patients and HCWs who have infectious TB

If a patient who has active TB is examined in a health-care facility and the illness is not diagnosed correctly, resulting in failure to apply appropriate precautions, or if an HCW develops active TB and exposes other persons in the facility, the following steps should be taken when the illness is later diagnosed correctly:

* To identify other patients and HCWs who were exposed to the source patient before isolation procedures were begun, interview the source patient and all applicable personnel and review that patient's medical record. Determine the areas of the facility in which the source patient was hospitalized, visited, or worked before being placed in isolation (e.g., outpatient clinics, hospital rooms, treatment rooms, radiology and procedure areas, and patient lounges) and the HCWs who may have been exposed during that time (e.g., persons providing direct care, therapists, clerks, transportation personnel, housekeepers, and social workers).

* The contact investigation should first determine if M. tuberculosis transmission has occurred from the source patient to those persons with whom the source patient had the most intense contact.

* Administer PPD tests to the most intensely exposed HCWs and patients as soon as possible after the exposure has occurred. If transmission did occur to the most intensely exposed persons, then those persons with whom the patient had less contact should be evaluated. If the initial PPD test result is negative, a second test should be administered 12 weeks after the exposure was terminated.

* Those persons who were exposed to M. tuberculosis and who have either a PPD test conversion or symptoms suggestive of TB should receive prompt clinical evaluation and, if indicated, chest radiographs and bacteriologic studies should be performed (Suppl. 2). Those persons who have evidence of newly acquired infection or active disease should be evaluated for preventive or curative therapy (Suppl. 2). Persons who have previously had positive PPD test results and who have been exposed to an infectious TB patient do not require a repeat PPD test or a chest radiograph unless they have symptoms suggestive of TB.

* In addition to PPD testing those HCWs and patients who have been exposed to M. tuberculosis because a patient was not isolated promptly or an HCW with active TB was not identified promptly, the investigation should determine why the diagnosis of TB was delayed. If the correct diagnosis was made but the patient was not isolated promptly, the reasons for the delay need to be defined so that corrective actions can be taken.

L. Coordination with the Public Health Department

* As soon as a patient or HCW is known or suspected to have active TB, the patient or HCW should be reported to the public health department so that appropriate follow-up can be arranged and a community contact investigation can be performed. The health department should be notified well before patient discharge to facilitate follow-up and continuation of therapy. A discharge plan coordinated with the patient or HCW, the health department, and the inpatient facility should be implemented.

* The public health department should protect the confidentiality of the patient or HCW in accordance with state and local laws.

* Health-care facilities and health departments should coordinate their efforts to perform appropriate contact investigations on patients and HCWs who have active TB.

* In accordance with state and local laws and regulations, results of all AFB-positive sputum smears, cultures positive for M. tuberculosis, and drug-susceptibility results on M. tuberculosis isolates should be reported to the public health department as soon as these results are available.

* The public health department may be able to assist facilities with planning and implementing various aspects of a TB infection-control program (e.g., surveillance, screening activities, and outbreak investigations). In addition, the state health department may be able to provide names of experts to assist with the engineering aspects of TB infection control.

M. Additional Considerations for Selected Areas in Health-Care Facilities and Other Health-Care Settings

This section contains additional information for selected areas in health-care facilities and for other health-care settings.

1. Selected areas in health-care facilities

a. Operating rooms

* Elective operative procedures on patients who have TB should be delayed until the patient is no longer infectious.

* If operative procedures must be performed, they should be done, if possible, in operating rooms that have anterooms. For operating rooms without anterooms, the doors to the operating room should be closed, and traffic into and out of the room should be minimal to reduce the frequency of opening and closing the door. Attempts should be made to perform the procedure at a time when other patients are not present in the operative suite and when a minimum number of personnel are present (e.g., at the end of day).

* Placing a bacterial filter on the patient endotracheal tube (or at the expiratory side of the breathing circuit of a ventilator or anesthesia machine if these are used) when operating on a patient who has confirmed or suspected TB may help reduce the risk for contaminating anesthesia equipment or discharging tubercle bacilli into the ambient air.

* During postoperative recovery, the patient should be monitored and should be placed in a private room that meets recommended standards for ventilating TB isolation rooms.

* When operative procedures (or other procedures requiring a sterile field) are performed on patients who may have infectious TB, respiratory protection worn by the HCW must protect the field from the respiratory secretions of the HCW and protect the HCW from the infectious droplet nuclei generated by the patient. Valved or positive-pressure respirators do not protect the sterile field; therefore, a respirator that does not have a valve and that meets the criteria in Section II.G should be used.

b. Autopsy rooms

* Because infectious aerosols are likely to be present in autopsy rooms, such areas should be at negative pressure with respect to adjacent areas (Suppl. 3), and the room air should be exhausted directly to the outside of the building. ASHRAE recommends that autopsy rooms have ventilation that provides an airflow of 12 ACH (47), although the effectiveness of this ventilation level in reducing the risk for M. tuberculosis transmission has not been evaluated. Where possible, this level should be increased by means of ventilation system design or by auxiliary methods (e.g., recirculation of air within the room through HEPA filters) (Suppl. 3).

* Respiratory protection should be worn by personnel while performing autopsies on deceased persons who may have had TB at the time of death (Section II.G; Suppl. 4).

* Recirculation of HEPA-filtered air within the room or UVGI may be used as a supplement to the recommended ventilation (Suppl. 3).

c. Laboratories

* Laboratories in which specimens for mycobacteriologic studies (e.g., AFB smears and cultures) are processed should be designed to conform with criteria specified by CDC and the National Institutes of Health (59).

2. Other health-care settings

TB precautions may be appropriate in a number of other types of health-care settings. The specific precautions that are applied will vary depending on the setting. At a minimum, a risk assessment should be performed yearly for these settings; a written TB infection-control plan should be developed, evaluated, and revised on a regular basis; protocols should be in place for identifying and managing patients who may have active TB; HCWs should receive appropriate training, education, and screening; protocols for problem evaluation should be in place; and coordination with the public health department should be arranged when necessary. Other recommendations specific to certain of these settings follow.

a. Emergency medical services

* When EMS personnel or others must transport patients who have confirmed or suspected active TB, a surgical mask should be placed, if possible, over the patient's mouth and nose. Because administrative and engineering controls during emergency transport situations cannot be ensured, EMS personnel should wear respiratory protection when transporting such patients. If feasible, the windows of the vehicle should be kept open. The heating and air-conditioning system should be set on a nonrecirculating cycle.

* EMS personnel should be included in a comprehensive PPD screening program and should receive a baseline PPD test and follow-up testing as indicated by the risk assessment. They should also be included in the follow-up of contacts of a patient with infectious TB.*

__________ * The Ryan White Comprehensive AIDS Resource Emergency Act of 1990, P.L. 101-381, mandates notification of EMS personnel after they have been exposed to infectious pulmonary TB (42 U.S.C. 300ff-82.54 Fed. Reg. 13417 [March 21, 1994]).

b. Hospices

* Hospice patients who have confirmed or suspected TB should be managed in the manner described in this document for management of TB patients in hospitals. General-use and specialized areas (e.g., treatment or TB isolation rooms) should be ventilated in the same manner as described for similar hospital areas.

c. Long-term care facilities

* Recommendations published previously for preventing and controlling TB in long-term care facilities should be followed (60).

* Long-term care facilities should also follow the recommendations outlined in this document.

d. Correctional facilities

* Recommendations published previously for preventing and controlling TB in correctional facilities should be followed (61).

* Prison medical facilities should also follow the recommendations outlined in this document.

e. Dental settings

In general, the symptoms for which patients seek treatment in a dental-care setting are not likely to be caused by infectious TB. Unless a patient requiring dental care coincidentally has TB, it is unlikely that infectious TB will be encountered in the dental setting. Furthermore, generation of droplet nuclei containing M. tuberculosis during dental procedures has not been demonstrated (62). Therefore, the risk for transmission of M. tuberculosis in most dental settings is probably quite low. Nevertheless, during dental procedures, patients and dental workers share the same air for varying periods of time. Coughing may be stimulated occasionally by oral manipulations, although no specific dental procedures have been classified as "cough-inducing." In some instances, the population served by a dental-care facility, or the HCWs in the facility, may be at relatively high risk for TB. Because the potential exists for transmission of M. tuberculosis in dental settings, the following recommendations should be followed:

* A risk assessment (Section II.B) should be done periodically, and TB infection-control policies for each dental setting should be based on the risk assessment. The policies should include provisions for detection and referral of patients who may have undiagnosed active TB; management of patients with active TB, relative to provision of urgent dental care; and employer-sponsored HCW education, counseling, and screening.

* While taking patients' initial medical histories and at periodic updates, dental HCWs should routinely ask all patients whether they have a history of TB disease and symptoms suggestive of TB.

* Patients with a medical history or symptoms suggestive of undiagnosed active TB should be referred promptly for medical evaluation of possible infectiousness. Such patients should not remain in the dental-care facility any longer than required to arrange a referral. While in the dental-care facility, they should wear surgical masks and should be instructed to cover their mouths and noses when coughing or sneezing.

* Elective dental treatment should be deferred until a physician confirms that the patient does not have infectious TB. If the patient is diagnosed as having active TB, elective dental treatment should be deferred until the patient is no longer infectious.

* If urgent dental care must be provided for a patient who has, or is strongly suspected of having, infectious TB, such care should be provided in facilities that can provide TB isolation (Sections II.E and G). Dental HCWs should use respiratory protection while performing procedures on such patients.

* Any dental HCW who has a persistent cough (i.e., a cough lasting greater than or equal to 3 weeks), especially in the presence of other signs or symptoms compatible with active TB (e.g., weight loss, night sweats, bloody sputum, anorexia, and fever), should be evaluated promptly for TB. The HCW should not return to the work-place until a diagnosis of TB has been excluded or until the HCW is on therapy and a determination has been made that the HCW is noninfectious.

* In dental-care facilities that provide care to populations at high risk for active TB, it may be appropriate to use engineering controls similar to those used in general-use areas (e.g., waiting rooms) of medical facilities that have a similar risk profile.

f. Home-health-care settings

* HCWs who provide medical services in the homes of patients who have suspected or confirmed infectious TB should instruct such patients to cover their mouths and noses with a tissue when coughing or sneezing. Until such patients are no longer infectious, HCWs should wear respiratory protection when entering these patients' homes (Suppl. 4).

* Precautions in the home may be discontinued when the patient is no longer infectious (Suppl. 1).

* HCWs who provide health-care services in their patients' homes can assist in preventing transmission of M. tuberculosis by educating their patients regarding the importance of taking medications as prescribed and by administering DOT.

* Cough-inducing procedures performed on patients who have infectious TB should not be done in the patients' homes unless absolutely necessary. When medically necessary cough-inducing procedures (e.g., AFB sputum collection for evaluation of therapy) must be performed on patients who may have infectious TB, the procedures should be performed in a health-care facility in a room or booth that has the recommended ventilation for such procedures. If these procedures must be performed in a patient's home, they should be performed in a well-ventilated area away from other household members. If feasible, the HCW should consider opening a window to improve ventilation or collecting the specimen while outside the dwelling. The HCW collecting these specimens should wear respiratory protection during the procedure (Section II.G).

* HCWs who provide medical services in their patients' homes should be included in comprehensive employer-sponsored TB training, education, counseling, and screening programs. These programs should include provisions for identifying HCWs who have active TB, baseline PPD skin testing, and follow-up PPD testing at intervals appropriate to the degree of risk.

* Patients who are at risk for developing active TB and the HCWs who provide medical services in the homes of such patients should be reminded periodically of the importance of having pulmonary symptoms evaluated promptly to permit early detection of and treatment for TB.

g. Medical offices

In general, the symptoms of active TB are symptoms for which patients are likely to seek treatment in a medical office. Furthermore, the populations served by some medical offices, or the HCWs in the office, may be at relatively high risk for TB. Thus, it is likely that infectious TB will be encountered in a medical office. Because of the potential for M. tuberculosis transmission, the following recommendations should be observed:

* A risk assessment should be conducted periodically, and TB infection-control policies based on results of the risk assessment should be developed for the medical office. The policies should include provisions for identifying and managing patients who may have undiagnosed active TB; managing patients who have active TB; and educating, training, counseling, and screening HCWs.

* While taking patients' initial medical histories and at periodic updates, HCWs who work in medical offices should routinely ask all patients whether they have a history of TB disease or have had symptoms suggestive of TB.

* Patients with a medical history and symptoms suggestive of active TB should receive an appropriate diagnostic evaluation for TB and be evaluated promptly for possible infectiousness. Ideally, this evaluation should be done in a facility that has TB isolation capability. At a minimum, the patient should be provided with and asked to wear a surgical mask, instructed to cover the mouth and nose with a tissue when coughing or sneezing, and separated as much as possible from other patients.

* Medical offices that provide evaluation or treatment services for TB patients should follow the recommendations for managing patients in ambulatory-care settings (Section II.D).

* If cough-inducing procedures are to be administered in a medical office to patients who may have active TB, appropriate precautions should be followed (Section II.H).

* Any HCW who has a persistent cough (i.e., a cough lasting greater than or equal to 3 weeks), especially in the presence of other signs or symptoms compatible with active TB (e.g., weight loss, night sweats, bloody sputum, anorexia, or fever) should be evaluated promptly for TB. HCWs with such signs or symptoms should not return to the workplace until a diagnosis of TB has been excluded or until they are on therapy and a determination has been made that they are noninfectious.

* HCWs who work in medical offices in which there is a likelihood of exposure to patients who have infectious TB should be included in employer-sponsored education, training, counseling, and PPD testing programs appropriate to the level of risk in the office.

* In medical offices that provide care to populations at relatively high risk for active TB, use of engineering controls as described in this document for general-use areas (e.g., waiting rooms) may be appropriate (Section II.F; Suppl. 3).

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